CYPHER, J.
*770**862In this appeal we are asked to reconsider one tenet of our search and seizure jurisprudence: that a traffic stop constitutes a "reasonable" "seizure" for purposes of art. 14 of the Massachusetts Declaration of Rights where a police officer has observed a traffic violation, notwithstanding the officer's underlying motive for conducting the stop. See Commonwealth v. Santana, 420 Mass. 205, 649 N.E.2d 717 (1995). For the sound legal and practical reasons discussed below, we decline to depart from that tenet as the general standard governing the validity of traffic stops under art. 14. We affirm the denial of the defendant's motion to suppress, and we also affirm the judgment of conviction.
Facts. We recount the facts found by the motion judge, supplemented by uncontroverted testimony at the motion hearing. Commonwealth v. Cordero, 477 Mass. 237, 238, 74 N.E.3d 1282 (2017). On January 25, 2013, Whitman police Detectives Joseph Bombardier and Eric Campbell were conducting surveillance of a three-unit apartment building out of which they suspected drug activity was being conducted.1 At approximately 10:50 P.M. that evening, the detectives observed a vehicle park nearby, and its two occupants enter the building. Those same two individuals reemerged a few minutes later, returned to the vehicle, and drove away without the vehicle's headlights on. Bombardier instructed fellow Officer Gary Nelson to stop the vehicle for suspected drug activity. Nelson did so a few minutes later, upon observing the vehicle **863traveling above the speed limit along *771a road in Whitman.2 Nelson radioed Bombardier that he had stopped the vehicle.
When the detectives arrived, Nelson was standing at the vehicle's driver's side. Bombardier likewise approached the driver, and in doing so he noticed a strong odor of marijuana emanating from inside the vehicle. Bombardier asked the driver if she had any marijuana in the vehicle.3 She told him that she did not think so, and said that he could check. After instructing the driver to step out, Bombardier used his flashlight to search the interior of the driver's seat area. Finding nothing, he directed Campbell to ask the front seat passenger, the defendant, to leave the vehicle. When the defendant stepped out, Campbell observed what he believed to be a firearm under the front passenger seat.4 The officers arrested the defendant and the driver, placed them in separate cruisers, and advised them of the Miranda rights. Another officer later observed a plastic bag on the floor of the cruiser between the defendant's feet that appeared to contain "crack" cocaine. The defendant was subsequently indicted for possession with the intent to distribute cocaine, as well as with firearm offenses and other offenses with enhanced penalties.
Prior to trial, the defendant moved to suppress the evidence seized during the traffic stop. The motion judge held an evidentiary hearing, and thereafter, he denied the defendant's motion. In April, 2015, a jury convicted the defendant on the lesser included offense of cocaine possession, and he was sentenced to one year in jail. The defendant timely filed this appeal from the judgment of conviction, and on appeal, he challenges only the denial of his pretrial motion to suppress.
Discussion.5 The defendant challenges the denial of his motion to suppress on three grounds. First, he argues that the evidence **864against him should be suppressed as the product of a pretextual stop, where the Whitman officers stopped the vehicle the defendant occupied not because it was speeding, but because the police suspected that its occupants were involved in drug activity. The defendant contends that all such pretextual stops, which generally are legitimated on the basis of an observed civil traffic violation yet motivated by a desire to investigate suspected criminal *772wrongdoing as to which the police lack reasonable suspicion or probable cause to justify an investigatory stop, violate art. 14 and its protection against unreasonable seizures.6 On this point, the defendant asks that we overturn our decision in Santana, 420 Mass. 205, 649 N.E.2d 717, which holds that an observed traffic violation is itself a lawful basis for the police to conduct a traffic stop regardless of the officer's underlying motive.
Second, the defendant argues that the police impermissibly expanded the scope of the stop when detectives Bombardier and Campbell approached the vehicle during Nelson's traffic inquiry and asked the driver about the smell of marijuana. Last, the defendant challenges the motion judge's finding that the driver's consent to the search of the vehicle was freely and voluntarily given.
We review these arguments in turn. In doing so, "we adopt the motion judge's subsidiary findings of fact absent clear error, but we independently determine the correctness of the judge's application of constitutional principles to the facts as found." Commonwealth v. Catanzaro, 441 Mass. 46, 50, 803 N.E.2d 287 (2004).
1. Pretext. The parties dispute, as a threshold matter, whether the defendant adequately raised this issue before the motion judge. We conclude that he did. The first section of the defendant's memorandum of law in support of his motion to suppress **865asserted that "[t]he car stop was effectuated so that the occupants could be identified and the car searched." The motion judge's written opinion likewise acknowledged "[t]he defendant['s] argu[ment] that the stop for the traffic offense was a pretext." The fact that the defendant did not specifically state that he challenged the continued viability of Santana does not preclude our review of this issue, given both its treatment below and the fact that the motion judge was bound to apply Santana regardless of the defendant's position. See generally Commonwealth v. Vasquez, 456 Mass. 350, 357-358, 923 N.E.2d 524 (2010).7
Article 14, like the Fourth Amendment to the United States Constitution, guarantees "a right to be secure from all unreasonable searches[ ] and seizures."8 Because "[a] police stop of a moving automobile constitutes a seizure," Commonwealth v. Rodriguez, 472 Mass. 767, 773, 37 N.E.3d 611 (2015), that stop must be reasonable in order to be valid under the Fourth Amendment and art. 14. A passenger in a vehicle may challenge the constitutionality of a stop. See Commonwealth v. Quintos Q., 457 Mass. 107, 110, 928 N.E.2d 320 (2010), citing *773Brendlin v. California, 551 U.S. 249, 251, 127 S.Ct. 2400, 168 L.Ed.2d 132 (2007).
In Santana, 420 Mass. at 209, 649 N.E.2d 717, we articulated the current State constitutional standard for evaluating the validity of a traffic stop. Under that rule, called the authorization approach, a traffic stop is reasonable for art. 14 purposes "so long as the police are doing no more than they are legally permitted and objectively authorized to do," regardless of the underlying intent or motivations of the officers involved. Santana, supra, quoting United States v. Trigg, 878 F.2d 1037, 1041 (7th Cir. 1989), cert. denied sub nom. Cummins v. United States, 502 U.S. 962, 112 S.Ct. 428, 116 L.Ed.2d 448, 116 L.Ed.2d 449 (1991).9 Stated differently, under the authorization test, a stop is reasonable under art.
**86614 as long as there is a legal justification for it. We have long held that an observed traffic violation is one such justification. See, e.g., Commonwealth v. Bacon, 381 Mass. 642, 644, 411 N.E.2d 772 (1980) ("Where the police have observed a traffic violation, they are warranted in stopping a vehicle"); Commonwealth v. Amado, 474 Mass. 147, 151, 48 N.E.3d 414 (2016) (valid stop where "unlit registration plate"); Commonwealth v. Feyenord, 445 Mass. 72, 75, 833 N.E.2d 590 (2005), cert. denied, 546 U.S. 1187, 126 S.Ct. 1369, 164 L.Ed.2d 77 (2006) (valid stop where inoperable headlight in daylight); Santana, 420 Mass. at 207, 649 N.E.2d 717 (valid stop where defective taillight). Cf. Commonwealth v. Lora, 451 Mass. 425, 436, 886 N.E.2d 688 (2008), quoting Whren v. United States, 517 U.S. 806, 810, 116 S.Ct. 1769, 135 L.Ed.2d 89 (1996) ("the decision to stop an automobile is reasonable for Fourth Amendment purposes 'where the police have probable cause to believe that a traffic violation has occurred' "). As Santana makes clear, the authority to conduct a traffic stop where a traffic violation has occurred is not limited by "[t]he fact that the [police] may have believed that the [driver was] engaging in illegal drug activity." 420 Mass. at 208, 649 N.E.2d 717.
In the defendant's view, however, evaluating the reasonableness of a traffic stop on the basis of legal justification alone is not enough, because this creates the risk that the police might use an observed traffic violation as a pretext for investigating other suspected wrongdoing.10 In place of the authorization test, the defendant seeks a new art. 14 standard for traffic stops that looks beyond objective legal justification in order to examine the police's underlying motives for conducting the stop. Specifically, the defendant asks that when considering a motion to suppress a judge should examine whether a given traffic stop was only a pretext for the police's underlying "true" motive to investigate suspected criminal conduct, as to which *774the police lacked the requisite reasonable suspicion or probable cause to justify a bona fide investigatory stop. As the primary basis for this position, the defendant relies on a series of cases and academic articles discussing **867the connections between traffic stops and racial profiling. He also argues that because Massachusetts courts have considered the issue of pretext when evaluating the reasonableness of inventory or administrative searches, so too should they consider pretext when analyzing the validity of traffic stops. Before addressing these specific points, we examine the underpinnings of Santana 's authorization test.
Santana is predicated on the general constitutional principle, reflected in both art. 14 and Fourth Amendment jurisprudence, that "police conduct is to be judged 'under a standard of objective reasonableness without regard to the underlying intent or motivation of the officers involved.' " Santana, 420 Mass. at 208, 649 N.E.2d 717, quoting Commonwealth v. Ceria, 13 Mass. App. Ct. 230, 235, 431 N.E.2d 608 (1982).11 See Lora, 451 Mass. at 436, 886 N.E.2d 688, quoting Whren, 517 U.S. at 813, 116 S.Ct. 1769 ("Subjective intentions play no role in ordinary, probable cause Fourth Amendment analysis"); Ceria, supra, and cases cited. Evaluating the validity of police conduct on the basis of objective facts and circumstances, without consideration of the subjective motivations underlying that conduct, is justified in part based on the significant evidentiary difficulties such an inquiry into police motives would often entail. This would require that courts discern not only whether the police initially possessed some underlying motive that failed to align with the legal justification for their actions, but also whether the police were acting on that "improper" motive (i.e., the pretext), as opposed to the "proper" motive, when engaging in the challenged action. Both judges and legal commentators have questioned the ability of courts-venues of limited insight-to reach accurate and satisfactory answers to these questions, which may be more appropriately handled by psychologists or philosophers than lawyers.
**868See, e.g., United States v. Arra, 630 F.2d 836, 845, n.12 (1st Cir. 1980) (one "problem" with this subjective approach is "the premium it would place on dissemblance," and that "it may be little more than guesswork for a court to determine what the true motivation was"); 1 W.R. LaFave, Search and Seizure § 1.4(e) (5th ed. 2012) (there is "no reason to believe that courts can with any degree of success determine in which instances the police had an ulterior motive," and "[p]resence of an ulterior motive may show why an officer might want to depart from the usual procedure but does not show that he has done so").
The authorization test avoids this often-speculative probing of the police's "true"
*775motives, while at the same time providing an administrable rule to be applied by both law enforcement in the field as well as reviewing courts. Like its Federal counterpart, art. 14 must often "be applied on the spur (and in the heat) of the moment, and the object in implementing its command of reasonableness is to draw standards sufficiently clear and simple to be applied with a fair prospect of surviving judicial second-guessing months and years after an arrest or search is made." Atwater v. Lago Vista, 532 U.S. 318, 347, 121 S.Ct. 1536, 149 L.Ed.2d 549 (2001). The bright-line standard of legal justification achieves this by clarifying exactly when the police may conduct a traffic stop: where an officer has observed a traffic violation. "If this were not so, [a traffic stop's] validity could not be settled until long after the event; it would depend not only on the psychology of the arresting officer but on the psychology of the judge." United States v. McCambridge, 551 F.2d 865, 870 (1st Cir. 1977).12
Moreover, this rule also ensures that the same constitutional protections under art. 14 are afforded to all Massachusetts drivers where the same factual circumstances are present. As we observed in Santana, "the defendants' contention might yield the illogical result of allowing stops of nonsuspect drivers who violate motor vehicle laws, but forbidding stops of suspected criminals who violate motor vehicle laws." Santana, 420 Mass. at 210 n.3, 649 N.E.2d 717. Application of the exclusionary rule in these circumstances, **869as the defendant requests, would be contrary to that rule's purpose, which is to "deter intentional unconstitutional behavior." Lora, 451 Mass. at 439, 886 N.E.2d 688. Its effect here would be to deter the police from carrying out one of their primary objectives: investigating, within permissible legal boundaries, suspected criminal behavior.
Beyond these legal and practical justifications, Santana 's authorization test is grounded in sound policy. We have noted that "allowing police to make [traffic] stops serves [the] significant government interest" of ensuring public safety on our roadways. Rodriguez, 472 Mass. at 776, 37 N.E.3d 611. As Rodriguez more fully explains:
"[M]any of our traffic violation statutes regulate moving cars and relate directly to the promotion of public safety; even those laws that have to do with maintaining a vehicle's equipment in accordance with certain standards may also be safety-related.... Permitting stops based on reasonable suspicion or probable cause that these laws may have been violated gives police the ability to immediately address potential safety hazards on the road. Thus, although a vehicle stop does represent a significant intrusion into an individual's privacy, the government interest in allowing such stops for the purpose of promoting compliance with our automobile laws is clear and compelling" (citation omitted).
Id. at 776-777, 37 N.E.3d 611. Therefore, the fact that a traffic law has been violated is, generally speaking, a legally sufficient basis to justify stopping a vehicle, irrespective of any additional suspicions held by the officer(s) conducting the stop. See, e.g., Commonwealth v. Cruz, 459 Mass. 459, 465, 945 N.E.2d 899 (2011) ("officers validly *776'stopped' the car for parking in front of a fire hydrant, a civil traffic violation .... Thus, the officers' presence at the side of the car was appropriate" [citations omitted] ); Santana, 420 Mass. at 210, 649 N.E.2d 717 ("By driving an automobile with a broken taillight, the defendants took the risk of being stopped"). In that sense a traffic stop cannot be "arbitrary," because it is predicated on a driver violating a traffic law.13
Still, the defendant urges that we overturn Santana on the ground that the authorization test countenances pretextual stops **870-and more specifically, stops motivated by the race of the driver (i.e., racial profiling). In the defendant's view, this court's previous attempt to address the problem of racial bias in traffic stops, Lora, 451 Mass. at 444-447, 886 N.E.2d 688, has failed to provide a meaningful remedy. Lora held that where a driver produces "sufficient evidence to raise a reasonable inference," id. at 442, 886 N.E.2d 688, that the stop at issue "is the product of the selective enforcement predicated on race," evidence seized in the course of that stop must be suppressed under the exclusionary rule. Id. at 440, 886 N.E.2d 688. The surest way to effectively remedy that issue now, the defendant contends, is simply to do away with Santana's authorization test, and instead hold that all pretextual stops, regardless of the particular motive (whether it be the race of a driver, or, as here, a desire to investigate suspected criminal wrongdoing) violate art. 14. There are at least two deficiencies in this argument.
First, to the extent the defendant appeals to our consideration of the motivations underlying a traffic stop in the racial profiling context as a basis for doing so in this and similar cases, he ignores any distinction between art. 14 and the equal protection principles of arts. 1 and 10 of the Massachusetts Declaration of Rights. In Lora we observed that racial profiling "is at base a claim that [the police] selectively enforced the laws in contravention of the Fourteenth Amendment and arts. 1 and 10." Lora, 451 Mass. at 436, 886 N.E.2d 688. We permitted inquiry into officers' subjective motives in that case because Lora, unlike Santana or Whren, "involved a challenge to [a] traffic stop[ ] based on equal protection grounds." Lora, supra. At the same time, we observed that " '[s]ubjective intentions play no role in ordinary, probable cause Fourth Amendment analysis.' Our holding in [ Santana ] is not to the contrary." Id., quoting Whren, 517 U.S. at 813, 116 S.Ct. 1769. See Lora, supra, quoting Whren, supra ("the constitutional basis for objecting to intentionally discriminatory application of laws is the Equal Protection Clause, not the Fourth Amendment"). Thus, Lora makes clear that to the extent we do consider the purpose of a stop when assessing its validity, we do so pursuant to the equal protection principles of arts. 1 and 10-not art. 14's guarantee against unreasonable seizures-and only where a driver has alleged that race was the reason for the stop.
This brings us to the more obvious deficiency in the defendant's appeal to the racial profiling context: the fact that racial profiling is not an issue in this case. Unlike the Lora defendant, the defendant here has raised no allegation of impermissible **871discrimination, and he does not challenge the traffic stop on equal protection grounds. To the contrary, he acknowledges in his brief that he is "is not arguing (and has never argued) that he was racially *777profiled"14 (emphasis added). Although we certainly do not dispute, as a general matter, the enormity or relevance of the problem of racial profiling, it is not an appropriate basis for overturning our general art. 14 standard governing the reasonableness of traffic stops where the defendant has expressly disavowed any such argument that race was a factor in the stop at issue.
At the same time, the defendant and the concurring Justice raise considerable, legitimate concerns regarding racial profiling and the impact of such practices on communities of color. We share these sentiments, which echo those expressed by past members of this court. See, e.g., Lora, 451 Mass. at 444, 886 N.E.2d 688, and cases cited ("Justices of this court have expressed considerable concern about the practice of racial profiling in prior decisions"). We likewise acknowledge their valid questions regarding the lasting efficacy of Lora for addressing the issue of pretextual stops motivated by race, given that in the near-decade since that decision, we are not aware of a single reported case suppressing evidence under its framework. We take this opportunity to encourage lawyers to use the Lora framework in cases where there is reason to believe a traffic stop was the result of racial profiling. To the extent we must review the adequacy of our decision in Lora, however, or address these issues in depth, we wait to do so in a case where a driver has actually alleged and laid a proper foundation for a claim under Lora. We cannot evaluate the efficacy of the Lora framework without a record.
As an alternative basis for his request that we overturn Santana, the defendant cites cases from "other areas of criminal law" where he contends Massachusetts courts "identify pretext"-namely, searches conducted for the purposes of inventory or administrative regulation. But the defendant's conclusion that "there is no good reason for the distinction" between the constitutional analysis in these cases versus traffic stops ignores at least one reason. Inventory and administrative searches-as distinct from traffic stops, which involve only a temporary seizure, see Rodriguez, 472 Mass. at 773, 37 N.E.3d 611 -are unique in that they are **872conducted in the absence of probable cause or reasonable suspicion, for purely noninvestigatory reasons. See, e.g., Commonwealth v. Vuthy Seng, 436 Mass. 537, 550-555, 766 N.E.2d 492, cert. denied, 537 U.S. 942, 123 S.Ct. 342, 154 L.Ed.2d 249 (2002). In these contexts, the burden rests with the Commonwealth to demonstrate that the search "was conducted for some legitimate police purpose other than a search for evidence." Commonwealth v. Benoit, 382 Mass. 210, 219, 415 N.E.2d 818 (1981), S.C., 389 Mass. 411, 451 N.E.2d 101 (1983). From the start, then, consideration of an officer's "purpose" for conducting the search is relevant to an assessment of the lawfulness of the search itself. Thus, where it appears that the "sole purpose" of that search was in fact criminal investigation, rather than inventory or administrative regulation, any evidence unlawfully seized must be suppressed. See, e.g., Benoit, supra at 219, 415 N.E.2d 818 ("The record clearly reveals that the only purpose for the entry into this suitcase ... was to seize evidence. The search and seizure without a warrant was, therefore, illegal"); Commonwealth v. Ortiz, 88 Mass. App. Ct. 573, 576-577, 39 N.E.3d 458 (2015) (affirming suppression of evidence found in course of inventory search where officer testimony showed that "sole purpose of impounding and searching the defendant's vehicle and its *778contents" was to search "for evidence of drug activity without a warrant").15 A traffic stop poses no such question regarding the actual legal authority for the police conduct at issue, because, as mentioned, "[w]here the police have observed a traffic violation, they are warranted in stopping a vehicle." Bacon, 381 Mass. at 644, 411 N.E.2d 772. Cf. Whren, 517 U.S. at 811, 116 S.Ct. 1769 (declining to import principles of cases "addressing the validity of a search conducted in the absence of probable cause" to cases involving "police conduct that is justifiable on the basis of probable cause to believe that a **873violation of law has occurred").
Having considered the defendant's arguments, we decline to disturb our general rule that the reasonableness of a traffic stop under art. 14 is evaluated according to the authorization test articulated in Santana. Outside of the racial profiling context-as this case is-the reasonableness of a traffic stop does not depend upon the particular motivations underlying the stop. For the sound legal and practical reasons previously described, legal justification alone, such as an observed traffic violation, is sufficient.
Applying that principle here, the motion judge credited Nelson's testimony that before conducting the traffic stop at issue, Nelson observed the vehicle traveling above the speed limit. We therefore affirm the judge's conclusion that "the stop was warranted by the observed traffic violation." "The fact that the [police] may have believed that the defendants were engaging in illegal drug activity does not limit their power to make an authorized stop." Santana, 420 Mass. at 208, 649 N.E.2d 717.
2. Scope of the stop. In addition to challenging the legality of the stop itself, the defendant argues that the Whitman police exceeded the permissible scope of the stop when the plainclothes detectives joined Nelson at the scene and asked the driver about the odor of marijuana emanating from the vehicle. "In evaluating whether the police exceeded the permissible scope of a stop, the issue is one of proportion." Commonwealth v. Sinforoso, 434 Mass. 320, 323, 749 N.E.2d 128 (2001). "The nature of the stop, i.e., for a traffic offense, defines the scope of the initial inquiry by a police officer." Commonwealth v. Bartlett, 41 Mass. App. Ct. 468, 470, 671 N.E.2d 515 (1996). See Commonwealth v. Cordero, 477 Mass. 237, 241, 74 N.E.3d 1282 (2017) ("A routine traffic stop may not last longer than reasonably necessary to effectuate the purpose of the stop" [quotations and citation omitted] ). "Where an officer conducts an uneventful threshold inquiry giving rise to no further suspicion of criminal activity, he may not prolong the *779detention or expand the inquiry." Feyenord, 445 Mass. at 78 n.5, 833 N.E.2d 590.
As discussed, the stop at issue was justified based on Nelson's observation of the vehicle speeding. This defines the permissible scope of the officers' inquiry. The defendant fails to cite any authority suggesting that it was impermissible for the plainclothes detectives to join Nelson at the location of the stop. The stop remained constitutional so long as the officers did not exceed its permissible scope. There is nothing in the record to indicate that **874the "tasks tied to the traffic infraction ... [were already] complete [ ]," Rodriguez v. United States, --- U.S. ----, 135 S.Ct. 1609, 1614, 191 L.Ed.2d 492 (2015), by the time Bombardier and Campbell arrived, or that Nelson unnecessarily prolonged the stop to await the detectives' arrival. See Cordero, 477 Mass. at 242, 74 N.E.3d 1282 ("The police do not earn 'bonus time' to conduct additional investigations by an expeditious performance of the traffic-related investigation"). The motion judge found that the detectives arrived while "Nelson [was] standing at the driver's side of the vehicle." Nelson testified that, after stopping the vehicle, he explained to the driver that he had stopped her for speeding and requested her license and registration; she produced a registration certificate but was unable to produce a license. Nelson recalled that he had been speaking with the driver for "[a]pproximately a minute," and had yet to confirm her name and date of birth, see id. at 242, 74 N.E.3d 1282 (tasks during routine traffic stop reasonably include "confirmation of the identity of the driver"), when Bombardier and Campbell arrived and spoke to the driver about the smell of marijuana. At that point Nelson returned to his cruiser to confirm McGovern's information. Contrast id. at 247, 74 N.E.3d 1282 (continued detention of defendant unreasonable where "the investigation of the civil traffic violations" justifying stop "was complete").
We also reject the defendant's argument that Bombardier's question to the driver about the smell of marijuana fell beyond the permissible scope of the stop. That argument is foreclosed by this court's opinion in Commonwealth v. Cruz, 459 Mass. 459, 945 N.E.2d 899 (2011). Cruz was decided following the enactment of G. L. c. 94C, §§ 32L - 32N, which "changed the status of the possession of one ounce or less of marijuana from a criminal to a civil offense." Id. at 464, 945 N.E.2d 899. In Cruz, an officer who had conducted a valid traffic stop detected an odor of burnt marijuana as he approached the driver's side window; we held that the officer's "asking the driver whether he had been smoking marijuana" did not constitute an impermissible expansion of the scope of the stop, "because the officers could potentially have issued the driver a civil citation pursuant to G. L. c. 40, § 21D." Id. at 466, 945 N.E.2d 899.16 The stop at issue here took place in January, 2013-after the Cruz decision, while possession of **875marijuana remained a civil offense.17 As in Cruz, then, Bombardier did not exceed the scope of the stop when inquiring about the smell of marijuana emanating from the vehicle, given his authority to issue a civil citation. "Once in the process of making a valid stop for a traffic violation," as here, "officers *780are not required to 'ignore what [they] see[ ], smell[ ] or hear[ ].' " Cruz, 459 Mass. at 466, 945 N.E.2d 899, quoting Bartlett, 41 Mass. App. Ct. at 471, 671 N.E.2d 515.
3. Consent. The defendant argues that the evidence should be suppressed because the driver did not voluntarily consent to the search of the vehicle. See Commonwealth v. Podgurski, 386 Mass. 385, 390-392, 436 N.E.2d 150 (1982), cert. denied, 459 U.S. 1222, 103 S.Ct. 1167, 75 L.Ed.2d 464 (1983) (passenger may object to validity of vehicle search). A warrantless search such as this is presumptively unreasonable under both the Fourth Amendment and art. 14 unless one of the "few specifically established and well-delineated exceptions" to the warrant requirement apply. Commonwealth v. Johnson, 461 Mass. 44, 48, 958 N.E.2d 25 (2011), quoting Coolidge v. New Hampshire, 403 U.S. 443, 455, 91 S.Ct. 2022, 29 L.Ed.2d 564 (1971). A search authorized by consent is one such exception. See Commonwealth v. Buswell, 468 Mass. 92, 105, 9 N.E.3d 276 (2014). As with all warrantless searches, the Commonwealth bears the burden of proof that consent was "freely and voluntarily given," Commonwealth v. Krisco Corp., 421 Mass. 37, 46, 653 N.E.2d 579 (1995), quoting Bumper v. North Carolina, 391 U.S. 543, 548-549, 88 S.Ct. 1788, 20 L.Ed.2d 797 (1968), meaning it was "unfettered by coercion, express or implied." Commonwealth v. Harmond, 376 Mass. 557, 561, 382 N.E.2d 203 (1978) quoting Commonwealth v. Walker, 370 Mass. 548, 555, 350 N.E.2d 678, cert. denied, 429 U.S. 943, 97 S.Ct. 363, 50 L.Ed.2d 314 (1976). "Voluntariness of consent 'is a question of fact to be determined in the circumstances of each case.' " Id., quoting Commonwealth v. Aguiar, 370 Mass. 490, 496, 350 N.E.2d 436 (1976). As a question of fact, "it should not be reversed absent clear error by the judge." Commonwealth v. Gray, 465 Mass. 330, 343, 990 N.E.2d 528, cert. denied, --- U.S. ----, 134 S.Ct. 628, 187 L.Ed.2d 407 (2013), citing Commonwealth v. Carr, 458 Mass. 295, 303, 936 N.E.2d 883 (2010).
We discern no error here. The motion judge, who "was in the best position to assess the weight and credibility of the testimony given at the [suppression] hearing," Carr, supra, concluded that the driver freely and voluntarily consented to the search of the vehicle. This was based in part on the judge's finding that when **876Bombardier "asked [the driver] if she had any marijuana in the car. She told him she did not think so and said that he could check." The fact that the driver affirmatively offered the search naturally supports the judge's conclusion that her consent was voluntary. See Commonwealth v. Sanna, 424 Mass. 92, 97-99, 674 N.E.2d 1067 (1997) (concluding that "the police had properly entered the defendant's home on the consent given by the father"). Further, the record lacks any evidence to suggest that the officers' conduct during the vehicle stop was at all coercive. See Commonwealth v. Cantalupo, 380 Mass. 173, 177-178, 402 N.E.2d 1040 (1980). Contrast Carr, 458 Mass. at 302-303, 936 N.E.2d 883 (consent not voluntary where armed officers "completely blocked the only exit" from premises, officer who sought permission to search "signaled his distrust of the defendants," and request to search "sounded more like an order"). Finally, that the police did not inform the driver of her right to refuse does not, as the defendant argues, invalidate her consent. "The fact that a person is not informed by the police that he has a right to refuse to consent to an entry or search is a factor to be considered on the issue of voluntariness, but is not determinative of the issue." Sanna, 424 Mass. at 97 n.10, 674 N.E.2d 1067. Given the absence of record evidence to the contrary, we conclude that the motion judge *781did not err in finding that the driver freely and voluntarily consented to the search of the vehicle.
Conclusion. For the foregoing reasons, we affirm the denial of the defendant's motion to suppress the evidence against him. We also affirm the judgment of conviction of unlawful possession of a controlled substance.
So ordered.