I have an old used Craftsman upright 30 gallon oil-less 110V 5HP air compressor that I use regularly and its portable. I bought it off my local craigslist several years ago for $75. I can lean it back using its upright handle and roll it on its two wheels. I use it around the house and sometimes load it up on my truck and haul it to a farm where I'm doing some renovation work.
For removing lug nuts, its not the compressor, but the impact wrench being used. If you have a budget impact, it typically won't do the job, not matter what compressor you use with it. I have several Ingersoll-Rand 231 units in my shop and they do a great job for all types of automotive repairs. If you want a really great air impact, get a Ingersoll-Rand 2135TiMax. It weighs about 4 pounds and is one of the most powerful 1/2" impacts available on the market. Also, ensure that you are running 3/8" air hose with your air compressor and you should have no problem removing any lug nut on any car.