¶1concurring in result only.
¶2I concur in the result reached in the majority opinion to uphold defendant’s driving while impaired conviction. I disagree with its con-*759elusion that the trial court did not err in allowing Glover to testify that “defendant’s” blood alcohol concentration at the time of the accident was 0.08 using a retrograde average extrapolation rate.
¶3I. Average Data
¶4The State tendered evidence of an average alcohol elimination rate data to prove defendant’s actual alcohol elimination rate and establish his blood alcohol concentration at the time of the accident. Unlike the defendant in State v. Gatoe, defendant here specifically objected to Glover’s qualifications and argued that his testimony lacked foundation. 78 N.C. App. 167, 168, 336 S.E.2d 691, 692, disc. rev. denied, 315 N.C. 186, 338 S.E.2d 107 (1985) (expert’s qualifications were “not contested” and “ [defendant's objections to the contested testimony were only general.”); see also State v. Davis, 142 N.C. App. 81, 90, 542 S.E.2d 236, 241, disc. rev. denied, 353 N.C. 386, 547 S.E.2d 818 (2001) (“Defendant did not object to [the expert’s] qualifications.”). Since we held in Gatoe, “[t]he assignment [of error] is not properly before this Court,” the remaining discussion in the opinion is obiter dicta and is not binding as precedent at bar. 78 N.C. App. at 168, 336 S.E.2d at 692.
¶5The trial court admitted, over defendant’s specific objection, Glover’s testimony that “defendant’s” elimination rate was 0.0165 and also that “defendant” had a 0.08 at the time of the accident. Glover relied on “an average extrapolation rate,” pure hearsay, instead of defendant’s actual elimination rate to reach his conclusions. Glover failed to establish any connection or common attributes to correlate the average extrapolation rate to defendant’s actual rate to establish relevancy.
¶6Recently, our Supreme Court clarified the test for admissibility of expert testimony:
The most recent North Carolina case from this Court to comprehensively address the admissibility of expert testimony under Rule 702 is State v. Goode, 341 N.C. 513, 461 S.E.2d 631 (1995), which set forth a three-step inquiry for evaluating the admissibility of expert testimony: (1) Is the expert’s proffered method of proof sufficiently reliable as an area for expert testimony? Id. at 527-29, 461 S.E.2d at 639-40. (2) Is the witness testifying at trial qualified as an expert in that area of testimony? Id. at 529, 461 S.E.2d at 640. (3) Is the expert’s testimony relevant? Id. at 529, 461 S.E.2d at 641.
¶7*760Howerton v. Arai Helmet, Ltd., 358 N.C. 440, 458, 597 S.E.2d 674, 686 (2004) (emphasis supplied). Defendant argues Glover laid no foundation for his testimony because he failed to show any relevance in using the average rate data as it applied to defendant. I agree. The use of average elimination data, instead of defendant’s actual elimination rate, is hearsay, irrelevant, and inadmissible under our Supreme Court’s holdings in Goodeand Howerton.
¶8Our Supreme Court has rejected average data as evidence to show how a specific action may have occurred or how an individual may have reacted or responded in an “actual set of circumstances.” Hughes v. Vestal, 264 N.C. 500, 505, 142 S.E.2d 361, 365 (1965). In Hughes, our Supreme Court addressed the admission into evidence of a chart showing average stopping distances. The Court rejected the use of these charts at trial and held:
A formula, in which so many components are variables and in which there is only one constant (rate of speed), cannot by projection of a positive result (distance), based on speculative averages, be of sufficient accuracy and relevancy to rise of its own force to the dignity of evidence in an actual set of circumstances. This and its hearsay character have led to its rejection as evidence in a large majority of the jurisdictions where the question has been directly raised.
¶9Id.The Court stated, “The factors involved in stopping automobiles are so many and varied that a fixed formula is of slight, if any, value in a given case.” Id.The Court reiterated that numerous variables affect the outcome in specific situations, including the vehicle’s weight, condition of tire tread, force of brakes, and types of roadways. Id.
¶10Similarly, Glover admitted that numerous variables exist to determine an individual’s alcohol elimination rate, including, among other things, a person’s: (1) gender; (2) height; (3) weight; (4) age; (5) elapsed time since eating; (6) “recent consumption” of alcohol; (7) type of alcohol consumed; and (8) “a person’s experience with alcohol.” Glover testified that an individual’s elimination rate “could be different within a given individual on different days.” Glover further testified that “the ideal way [to know defendant’s elimination rate] would be to get multiple samples at the time of the event, the arrest or the crash . . . [or] do a controlled experiment where you . . . measured it.” Glover neither identified nor correlated any similarities between defendant and those out of court persons *761tested during the experiments that collectively led to the “average” elimination rate.
¶11In Catoe, we recognized, “usual constraints of relevance continue to apply.” 78 N.C. App. at 170, 336 S.E.2d at 693. Average data is hearsay, purely circumstantial, and irrelevant'to defendant’s alcohol elimination rate and blood alcohol concentration at the time of the accident. The State failed to prove the relevance of Glover’s average data testimony. Glover had neither personal knowledge nor any foundation to testify that defendant’s rate of eliminating alcohol from his body is 0.0165 per hour. See Howerton, 358 N.C. at 458, 597 S.E.2d at 686. Glover’s opinion that defendant’s blood alcohol concentration was 0.08 at the time of the accident was also without foundation. Defendant’s breathalyzer test showed 0.05, well below the “0.08 or more” alcohol concentration required for conviction under the statute. N.C. Gen. Stat. § 20-138.1(a)(2) (2003).
¶12Glover failed to show how another out of court individual’s or the average of a group of other individuals’ alcohol elimination rates were relevant to defendant’s rate on the date of the accident. The trial court erred in admitting this testimony. See Howerton, 358 N.C. at 458, 597 S.E.2d at 686. Glover’s use of a “conservative rate” does not cure the hearsay defect or establish relevancy. Glover also failed to lay a foundation by correlating the average rates to defendant’s age, sex, height, weight, or any other physical characteristic to establish relevancy to be admitted into evidence. If Glover’s testimony on average rates was the sole basis for the jury to return a guilty verdict on defendant’s having a blood alcohol concentration of 0.08 or more, his conviction must be reversed.
¶13II. Presentation of Issues to the Jury
¶14The trial court instructed the jury pursuant to N.C. Gen. Stat. § 20-138.1(a) (2003) that it should convict defendant if it found beyond a reasonable doubt that he operated a vehicle either: “under the influence of an impairing substance or had consumed sufficient alcohol that . . . defendant had an alcohol concentration of 0.08 or more ....” The issues, however, were not submitted to the jury separately. Further, the jury’s verdict does not reflect which prong of the statute they found defendant violated. As defendant failed to request separate instructions, object to the trial court’s instructions, assign error to the instructions, or argue plain error, this issue is not reviewable. Despite a clear indication in the record that the jury returned an unanimous verdict of either, or both, a 0.08 blood alcohol concentra*762tion or an appreciable impairment, defendant failed to preserve this error and waived his right to appellate review of the jury instructions. See N.C.R. App. P. 10(b)(2) (2004). Where the evidence shows defendant may have consumed a combination of alcohol and another impairing substance, the better practice is for the trial court to submit the issues separately to the jury to determine whether defendant operated a vehicle: (1) “[w]hile under the influence of an impairing substance;” or (2) “[a]fter having consumed sufficient alcohol that [defendant] has ... an alcohol concentration of 0.08 or more.” N.C. Gen. Stat. § 20-138.1(a)(l)-(2) (2003).
¶15III. Conclusion
¶16The trial court erred in admitting Glover’s testimony of defendant’s extrapolation rate and blood alcohol concentration based on irrelevant average data. Average data alone is hearsay, not relevant, and insufficient to prove defendant’s alcohol extrapolation rate and blood alcohol concentration level at the time of the accident. Without proving the relevance of this average data as it relates to defendant’s actual elimination rate, Glover lacked a foundation to offer this portion of his testimony. Defendant was denied his right to confront and cross-examine these hearsay declarations, which formed the basis for Glover’s average data and were introduced to prove the truth of the matters asserted. In light of the other substantial evidence presented at trial and defendant’s failure to object to the presentation of issues to the jury, this error was harmless.
¶17Other testimony sufficiently supports the jury’s conviction of defendant under N.C. Gen. Stat. § 20-138.1(a)(1) of driving “[w]hile under the influence of an impairing substance.” See State v. Coker, 312 N.C. 432, 440, 323 S.E.2d 343, 349 (1984) (N.C. Gen. Stat. § 20-138.1 creates one offense that “may be proved by either or both theories.”); see also State v. Mark, 154 N.C. App. 341, 346, 571 S.E.2d 867, 871 (2002), aff'd, 357 N.C. 242, 580 S.E.2d 693 (2003) (“The opinion of a law enforcement officer . . . has consistently been held sufficient evidence of impairment....”). Trooper Davis testified that defendant smelled of alcohol, stared at him with a “blank face,” fumbled through his papers, and needed assistance in getting to the patrol car. Trooper Davis also testified defendant was “swaying” during the “walk-and-turn” test, as well as during the “sway test.” Trooper Davis found ten empty packages of Guaifenesin tablets on defendant. Glover testified as an expert on the combined effect of these tablets and alcohol. This evidence is sufficient to support *763defendant’s driving while impaired conviction under N.C. Gen. Stat. § 20-138.1(a)(l).
¶18I concur in the result reached by the majority opinion and vote to sustain defendant’s conviction.