Whatever you choose, make sure it comes with a
long crevice tool attachment, or is adaptable to one you can buy separately, if you want to get at all the carpet between the seat and console in just about any car. The standard crevice tools that come with vacs often don't quite reach.
I'm unfashionably old school.

Have you considered a corded ShopVac or other like vacuum if you've got a little spot for it in the garage? I keep a 6 gallon / 3 hp corded wheeled ShopVac in the corner and use that when I'm doing thorough vac jobs on the cars. It never runs out of juice, provides good suction, I've tripped it over the cord a few times and it keeps on ticking, and once you're done with the cars you can vac the garage floor! I have an older model similar to the following that's been humming along for a decade or more:
https://www.amazon.com (commissions earned)
For something like that you'd have to buy a long crevice tool and a brush attachment separately, around $15.
I've also got one of the following attached to the wall next to an outlet which comes in handy for extra reach around to the liftgates among other handy uses:
https://www.amazon.com (commissions earned)
When I just want to vac the front mats or pick up a some random junk I grab the laundry room unit which is decently powerful, has a flip up brush, and has good run time, an impressive little unit:
And just when I thought I was running out of things to talk about....
