I like the Viair portable compressors. I got my wife the Viair 75P portable compressor to keep in her Subaru. It's only 50 PSI max, but that's plenty for a passenger car or for an ATV. It's significantly quieter, faster, and more reliable than the Harbor Freight models or the cheap stuff sold at the local hardware stores. It draws a max of 10 amps, so it will plug into the cigarette lighter plug of just about any vehicle on the road. It's rated for a 100% duty cycle at 50 PSI. One big reason for choosing this particular model was that it is permanently mounted inside it's hard-shell carrying case, so less likely to get damaged kicking around in the trunk.
Here's the link to the manufactures page on this model:
75P Portable Compressor | VIAIR® Corporation
You can find them at Northern Tool or on Amazon for about $63.
I liked it enough that I got another Viair compressor to keep in my truck: the
Viair 88P. Higher pressure, higher flow rate. Has no problem with my larger truck tires. Runs about $90. It does draw enough amps that you need to connect to the battery with the included battery clamps. This is in a soft case, and you take the compressor out when in use.
I just noticed that Viair now makes a model 88P-SXS designed for use on a SXS UTV. Same specs as the regular 88P, but has a 2 pin SAE connector on the power cord (similar to what is used on some battery charger/maintainers). It comes with a set of ring terminals with the mating connector for permanent connection to the battery as well as a set of battery clamps so you can connect those for use with other vehicles. If I connect the ring terminals, I can use the same connection to hook up a battery maintainer.
