difference between pressure washer and 12v pump

[ricadodetail]

I have a 12v water pump. 15gallon capacity tank. It shoots out 1gallon per minute(gpm). I use it instead of the pressure washer due to cost of big tank and pressure washer. Way i wash cars i take my two five galln buckets one with soap another with water to clean mitt. Wetting the car and washing away the soap i use about 4 gallons tops per car and no soap whatsoever is on the car. My question is those who use a pressure washer is a car easier to use with pressure washer? How much water do you guys use per car?

[oasis mobile]

I use way more water then that , I have a 100 gallon tank and can squeeze maybe 10/11 cars out of that 100 gallons.
I like the pressure washer because I can blast off the heavy road grime.