Best cars to buy used: Many are luxurious The BMW 5-Series leads iSeeCars' list of the top cars to buy used over new. Photo courtesy of BMW. Wednesday, Mar. 31, 2021, 03:24 PM By Auto Remarketing Staff WOBURN, Mass. - The BMW 5 Series is the best car to buy used over new, according to a new study from car search engine iSeeCars.com. The 5 series led iSeeCars’ list of the top 15 cars with the greatest change in price between gently used and new versions. The BMW 5 Series midsize sedan is joined by another BMW sedan, the compact 3 Series, in the No. 9 spot. The third-ranked Infiniti Q50, seventh-ranked Infiniti Q60 and the 10th-ranked Mercedes-Benz CLA were additional luxury sedans on the list.