He always drove, he never sat as a passenger in her car. When they went somewhere, they took his truck.
Suzanne did however drive the girls places, and the DNA in the back seat probably matches MM2's BF (IMO, just a guess - but the stepfather of that boy implied that the boy spent quite a bit of time with the Morphews).
Glove compartment DNA was probably from a car wash or dealer service/detailing.
I believe the bike repair guy would not have been required to provide DNA and probably not fingerprints, either.