He could have used it to transport Danielle to Dehesa Road. In so doing he implicates Barbara, maybe there exists evidence from Danielle in her car. He certainly had enough time to drive there, back, and clean up.
There is still a question whether Denise locked that side yard/garage door. Denise said Denise didn't lock it, just closed it. Brenda thought Denise locked it. Maybe when Damon at 3:30Am checked that door, said it looked locked. At that time he might have actually left it unlocked and closed. Why--to possibily point the finger of blame on the girls who could have come back and kidnapped Danielle. Remember the drag marks outside of the door by the side yard (little denise would have had to drag Danielle not carry her)and their was blood out there. Also, Damon called Denise the next day said the police wanted to talk to her about that "door". Why, because Damon needed to point the police toward Brenda and Barbara and away from himself. -This could be-
Those transcripts from the hearing are up - here's a relevant part...
MR. FELDMAN: YOUR HONOR, BUT WHILE WE'RE STILL HERE, IF I MAY, THERE'S AN ISSUE OF REBUTTAL, TOO. THE PROSECUTION HAS GIVEN US MANY OTHER WITNESSES, AND WE WANT TO MAKE SURE THAT THERE'S NO SANDBAGGING. THEY KNOW WE'RE CALLING FAULKNER OR WE'RE LIKELY TO CALL FAULKNER WHO IS THE FORENSIC ENTOMOLOGIST WHO'S WRITTEN A REPORT THAT SPECIFICALLY SAYS DANIELLE VAN DAM COULD NOT HAVE BEEN IN THE LOCATION SHE WAS ANY SOONER THAN THE 16TH. THAT'S WHAT THE REPORT --
MR. CLARKE: EXCUSE ME, YOUR HONOR. THAT'S ABSOLUTELY INCORRECT.
MR. DUSEK: WHAT HE SAYS IS UNIMPORTANT AT THIS POINT UNLESS WE'RE TRYING TO INFLUENCE THE JURORS OUT THERE WATCHING THIS ON T.V.
THE COURT: THEY BETTER NOT BE WATCHING IT ON T.V.
MR. FELDMAN: I WOULD HOPE NOT...