If there's someone out there who wants to wash Koichi's car, please email us at firstname.lastname@example.org.
While I waited for the car wash to finish, the part-timer kept yacking at me and it was really annoying.
Who would buy a car wash business to launder money?
A wash that washes cars is a car wash.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well. Don't confuse this with the same-sounding 戦車 though... unless you're washing your 戦車 in a 洗車...