What is the best small unit for doing extraction?
they'll all work for car detailing
what he should be looking for is a porty with clamshell design. (most of 'em are now-a-days)
minimum of 6 gal fresh water tank(9-12 gal would be better)
and two 2 stage vacs minimum
don't have to spend a ton of money (don't need an over engineered $3000+ porty)
$1200 to $1500 will get you one that's more than suitable for car detailing
Check out
EDIC units
..L.T.A.