I have had a gas powered 6.5 HP, 2200 psi, 2 gpm for about 4 or 5 years.
It is a Campbell Hausfeld commercial unit. I think it was on sale for about $300 at the time I bought it. I don't even know if CH is still in the business.
I pressure washed two houses, one garage, a very large deck and a pontoon boat with it. Did a great job.
Since then, I have never used it. Probably hasn't been started in 2 or 3 years.
It might be a good investment for you, but I probably should have just rented one.
I have never used it on the vehicles. If I feel I need to pressure wash them, (rarely happens), I go to the DIY spray wash. The only thing I ever pressure wash on the vehicles would be wheel wells or under carriage.
Not exactly a ringing endorsement.