I've got a pressure washer with a Honda 6 or 6.5 hp engine; I think it'* like 2400 or 2700 psi (don't remember exact model). I use it on the car.
Just be careful on nozzle selection. The 40 degree is fine for the body, and the 30 degree is ok for underbody/wheelweel and wheels/tires. But the 15 degree can peel paint off wood, and the 0 degree will bore holes in concrete, so I stay away from those on the car.
I use it on the engine compartment also, though ONLY with the 40 degree nozzle, and not too close (for fear of cutting wires, etc.)
2004 Buick Lesabre Limited, Gran Touring; Bone Stock
1998 Buick Lesabre Limited, Gran Touring; Mods: Poly sway bushings/endlinks, Tru-Cool trans cooler, Thrasher shift kit (med), PLIM, front PEM; Mods in progress: Alot of stuff, but slowly...