Until recently, every since they were invented, 12v air compressors just stunk, IMO.
Cheap, hot, slow, terrible chuck, etc. maybe a pressure gauge and some useless clip to hold the chuck on the tire valve, or else I'd get to hold it on myself for the 9 minutes, plus, it take to pump up a tire. Some did not even have a power switch just plug them in and wait for the cord to overheat.
Not any more.
These HF compressors are awesome. They are relatively inexpensive, come in a nice carry bag, have a decent coiled hose with a quick connect air coupler.
They are solidly built, nice switch, good gauge. The best part is the nice brass chuck, that THREADS on to the tire valve.
Hook it up turn it on, relax and keep an eye on the gauge, for the 5 minutes or so, it takes to pump up a flat car tire, not too bad considering the compressor piston bore is probably the size of a quarter.
Definite pass. This is the second-to-smallest size, but it works great. They have larger models also. I'll buy a bigger one, next time, if this one ever wears out.
http://www.harborfreight.com/12v-100-psi-high-volume-air-compressor-69284.html