Nascar: true paint or plastic sheet?
Depends on the paint scheme. Some teams have cars that are still a combination of paint of decals, while others a full body wrap. For example, the two main paint schemes for the #48 Lowe's car are blue (Lowe's) and black (Kobalt). The car is painted that single color with decals for stripes, numbers, sponsors, etc. The same is true for the #78, which just has a simple matte black finish paint scheme. Since they use these schemes regulalrly, its cheaper and easier to paint the car. In contrast, a team like the #18 or the #99 that uses multiple sponsors throughout the year, and have very detailed schemes (i.e. the MMs car), will utilize the full body wraps so they can quickly, and easily change the look of the car as necessary should the turnover to the next race be short (e.g. using the same car the next week for similar track but have different sponsor). Edit: Contrary to other answers, not all teams use wraps these days. I was in the garage just a few weeks ago at Michigan and spoke to the 48 team while they were in the inspection line. Their cars are painted.
Depends on the team, the sponsor, and the race track. Most, if not all, of the short track cars are wrapped. Daytona and Talladega are the two tracks teams will use paint over a wrap. Paint is lighter than a sheet of plastic and every little bit counts.
Generally there a combination of both, the basic colors are laid down in paint, (Cheaper) then the fancy graphics are done in the vinyl wrap. if really intricate then its all done in vinyl wrap, I've painted a few race cars in my day, I remember when the vinyl wraps first started coming out, but then again I remember when Infinion was still called Sears Point, That's where I use to work, Retired from the trade now, but I still have a few buddy's that work in the shops there, and we still like to sit around drinking beer and telling each other lies. the weight thing is BS, they all meet a minimum weight requirement, most have to add ballast to meet the requirement, unless of course your Tony Stewart, with the Formula open wheel cars the only reason for a minimum of paint and Vinyl not allowed is so the tech inspectors can see any cracks or fatigue in the carbon fiber drivers tubs, a maximum of 0.050mm paint thickness was allowed, which requires a very high solids paint to get correct coverage, there was actually some math involved and this paint was not cheap,
They are wrapped in plastic sheets that give them their color and designs
