I have mentioned this before in passing but had my old camera handy today (which misted up after getting damp)
take one hoselock dial sprinkler
place on drive way....
And run the car back and forth (either moving sprinkler or car to ensure you get the whole underside)
Bit dark but you get the gist
the amount of muck it removes shows it must be doing a reasonable job till it warms up and i can bare to crawl around on the drive with the pressure washer
just try not to run over the sprinkler as they dont tend to like it
take one hoselock dial sprinkler
place on drive way....
And run the car back and forth (either moving sprinkler or car to ensure you get the whole underside)
Bit dark but you get the gist
the amount of muck it removes shows it must be doing a reasonable job till it warms up and i can bare to crawl around on the drive with the pressure washer
just try not to run over the sprinkler as they dont tend to like it