There are quite a few vehicles that have 120v outlets built in. I know many mini-vans do.

From what I've seen though, most aren't very powerful. 100 watts at most. Enough to run, say, a small laptop. You could probably charge about 8 or 9 phones at the same time though.

Depending on the fuse size on your cigarette lighter, you can typically run a larger inverter than that. A 10amp fuse will allow a ~120 watt inverter. A 15 amp fuse will allow a ~180 watt inverter. A 20amp fuse will allow a ~240 watt inverter.

Years ago I bought a little 225 watt inverter for my truck, which has a 20amp cigarette lighter receptacle. I would use it to charge electronic devices (like my laptop) while on the road.

While you can't power a house off it, it worked great for charging small electronic stuff or running a small TV/DVD player.