I was trained to do wraps among all the other techniques taught at the 3M Professional Installer course I took several years ago. However, I found that designing, printing and installing them was just too time consuming and I could make much more money sticking with signs and banners.
Fully agreed. We've been doing wraps for about 14 years, but discontinued them about a year ago. Material costs have gone up a lot (if you can even find the vinyl you need -- and good luck finding vinyl for color changes without special ordering full rolls and waiting weeks or months for delivery). Reliable labor is hard to find, and the amount of time spent (from start to finish) just isn't that profitable for a small sign shop compared to banners/yard signs/etc..
For example, say you have a $3.5k wrap (above average price for a standard passenger vehicle in my area), and it costs $1,850 in vinyl (50 yard rolls of 3M IJ180 + 8518)+ $150/ink. (Granted you'll have some material left over.) You've got 1.5k left to work with -- if everything goes to plan and nothing has to be reprinted -- spread across 30 to 40 hours of design, prep, install. That means you're grossing $37.50/hour for some of very tedious and unforgiving work, which probably won't come close to covering shop overhead.
I won't go into detail about the many challenges of wrapping vehicles (e.g. vehicles with very breakable plastic parts, wrapping doorjambs, dealing with warranties, etc.), but it's tough. And you need someone experienced enough to not damage vehicles in the process.
Can it be profitable? Sure, with the right shop setup, temp. controlled garage / lighting, a lot of learning (up front and ongoing), and a really optimized work flow. Is it worth it? Not for my shop. I can afford to be picky about my jobs, so I axed the least profitable work (wraps). But if you can do a very professional job and command top dollar for it... then maybe it could work out?