You can live with almost any air compressor but you will have to sit and wait from time to time. You have asked a question that no one can really answer for you. i worked for years with a compressor from a two ton window unit and a large freon drum. i even painted a 55 chevy with the contraption. I went to an 80 gallon compressor from Home depot 30 years ago and it is still running. It takes up the corner of the room and is loud when it runs. It has no trouble keeping up with a paint gun but isnt anywhere near big enough to sandblast all day, or even run a die grinder non stop.
The point is that likely you will buy an air compressor and soon find out it isnt big enough because you buy an air hammer or a good die grinder. then you move up in size but still cant run a sand blaster.
I painted a lot of cars with my old mans 7 gallon Craftsman compressor. But then I also painted one with an airless one time.
If you are the kind of gut that will always have car projects running and will be in your garage constantly for the rest of your life, buy the biggest air conpressor you can afford. You need to consider the loss of space, the encreased electrical service, the noise, and how you will honestly use it. (you should get at least a compressor that requires 20A 240V, 30A would be better.)
If all you are going to do is paint a car every couple of years, fill tires, and use an impact to remove a subborn bolt every once in a while then the chances are you can get by with a little 7 gallon 110V 15A unit, you will just have to wait on it from time to time. Heck, If I remeber right the 7 gallon one will just about empty a paint gun before the air pressure drops to low and it will build back up in the time it takes you to refil. But it wont run an old two quart siphon production gun. Also be aware if you use it much you will wear out several of those little ones before you wear out a big one.
