For quick light pickups, we use the Dyson Handheld DC 16
It's very light, less noisy and cordless, perfect for couch, chair, window sill, car cabin...etc.
The newer models have longer batteries (10 minutes at 100% suction) and a new digital motor, The Animal model DC31 comes with a motorhead attachment like the upright brushbar, you can buy just the motorhead separately.
Here's a video review of the DC 31 Animal
If you want to want to buy a pet hair attachement (no motor) for other vacuums, there's the Ontel One (cheap)
There's also a Bissell pet combo pack Version (cheap)
And a corded handheld version Bissell Pet Eraser (cheap)
In my opinion / experience, the best way to clean in car cabin is a pair of dish washing rubber / latex gloves, static causes pet hair to stick, once you brush all the hair into a corner, you can either vacuum it or pick it up with your fingers. Pet hair "weaves" into carpet, low suction is not the problem, the lack of a motorhead / brushbar is what makes it hard to clean up.
Don't buy a handheld for big jobs.