My lovely bride gave me a Coleman Power Chill for my birthday. I'm impressed. It holds up to 48 cans of soda. It has an adjustable/removable shelf that makes item placement easier. It runs both standing up (like your home refrigerator) or on its back. It has a long 12V power cord so it can run in the back seat or trunk, plus an AC adapter for home use.
It's a little bit big for minimalist camping, but I intend to use it more for road travel than camping. It's a bit noisy, but won't be noticeable with ZZ Top blasting out my speakers.
It took a long time to cool down, so I will be sure to plug it in at home hours before any road trip. Also, it is recommended to have your food items pre-chilled before putting them in the Power Chill.
Of course, it runs non-stop, so it will drain the car battery if left on while parked. So it may not be suitable for perishables, but for soft drinks, having it shut down periodically isn't a problem. It cools to 40 degrees lower than ambient temperature, so if your car's A/C keeps the interior at 75 degrees, your drinks will be cold enough to give you a brain freeze.
So far, it seems to be a good product. I don't know what Mrs. paid, but I saw them at WalMart for $95. I've seen them online for a little less and a lot more.