I want to repaint my 2001 Lexus ES300. If I were to buy or rent an air compressor, what kind of specifications do I need for it? I.e. the minimum CFM, HP, etc.
I apologize for such a long answer. Your question is not simple.
Most higher quality coating for metal require a hardener, etc. This makes things more complicated. I would get someone more experience to do your paint job for you unless you plan to do a lot of painting in the future, then watch a lot of you tube videos or take some classes.
There are two type of paint spraying large amounts of coatings. There is airless paint sprayer or air sprayed paint.
Airless paint sprayers are basically the ones used to paint houses etc. They atomize the paint into tiny particles to fill every tiny gap and crevice. I would recommend using a small tip on the gun to get a nice slow flow of paint. if the paint comes out to fast you can get runs droplets from low pressure that will ruin your paint job. If you have never used a paint sprayer before I would practice on some other project before trying to paint metal.
If you are going to use the "classic movie" traditional body shop air compressed gun, You will need a massive tank that costs $800+. They need to be able to compress enough air to continuously work. The tanks at the store usually tell who what they are rated for. This method also requires you buy a special gun with a tank attacked to it where the paint is stored, it will come with a gravity fed reservoir (tank is above the gun) or a air displacing reservoir (tank is under the gun in front of trigger). The guns usually require 30-40 PSI. This needs to be continuous, if the pressure drops the guns does not atomize the coating like it should, causing larger (splatter) droplets to come out the tip which will ruin your paint job.
First you need to sand the car, then prime the car, then paint the car, then seal the car, last you need to polish the car. This is why paint jobs are so expensive. Some paints come with primer built in and can be purchased at auto parts stores. You will still need to spray a clear coat sealer and polish/ buff the car for hours.
There is a lot of skills that need to be learned to get a higher quality paint job. Also there is strict EPA regulations on capturing and filtering all the chemicals out to the air before being discharged to the exterior / public.
P.S. I recommend you search on craigslist for a body/paint guy who has the experience and is looking for extra work. They will usually do the same or similar quality work as a regular shop for a fraction of the price!