Dad’s short answer: Four things: a long crevice tool, a motorized brush head if you have pets, enough runtime to finish the whole car, and a bin you can empty one-handed. The crevice tool length is the one people forget and regret.

Why the crevice tool decides it

A car is mostly gaps. The rail under the seat, the seam where the seat back meets the base, the slot beside the center console, the footwell corners. A short stubby crevice tool reaches none of them, and those are exactly where the crumbs live.

An extra-long crevice tool is the difference between vacuuming your car and vacuuming the parts of your car you can already see. On the handheld I rated highest, the long crevice tool was one of the things I called out as a genuine plus.

Cordless is obviously non-negotiable here. And if pets ride in the car, the motorized brush head matters as much on seat upholstery as it does on your couch.

The practical stuff

Runtime. A full car interior takes longer than people expect. If the machine dies halfway through the back seats, you'll stop doing it.

Bin emptying. A push-button release you can work one-handed over a trash can beats one you have to twist apart. Small thing, used every time.

Whether it stands up on its own, which matters more than it sounds when you're working in a driveway with nowhere to set it down.

And filtration, if you're picking up fine dust rather than crumbs. Plenty of handhelds skip HEPA entirely and clog faster on fine material.

Dad’s Take: Look at the crevice tool first. In a car, reach beats suction every time.