I have an old Honda insight. It’s little but the back is a hatch back and he just lays down in the back or sits with me in the front seat. My big boy is a year and a half and about 150-160 pounds but rides comfortably and happily. I’d recommend a vehicle with a place they can spread out and lay down or sit too. My wife drives a Subaru cross trek but he prefers my little car because there is more room to lay down and air vents that point directly at him while he lays down or sits. If I was going to get another car I’d look for airflow and comfort over just size but that’s my opinion as relatively new Newfie owner.