Electric Pressure washer sans electricity

I don't think you will ever find out because the pressure washer has a plug with 2, or maybe 3, prongs that fit into a standard electrical 110 volt A/C (alternating current) outlet. Your car has a 12 volt D/C (direct current) power supply and the outlets, formerly called cigarette lighters, are round and incapable of accepting the plug from the pressure washer.

What is the current draw of the equipment you will use in your car? Typical small appliances can be used with most inverters. If you'll be using heavy-draw equipment like some large power tools or large TVs (over 13"), then you'll need a larger-capacity inverter and a direct connection to the battery. Best check your owner's manual or check with Toyota dealer. Safety issues should be no different than using anything electric around water-be careful. Does the power washer have a three prong outlet-suggesting that the mfg wanted users to plug it into a ground fault outlet, something not possible on a car.