Using his car would have been madness, in my view. He lived right in the middle of a village. Sleepy or not, anybody could have seen him. Even just going on foot is very risky. The bike is risky enough.
We will never know even if gulity.
If gulity he could just have had luck on his side. That nobody had identified him on his murderous travels..
I think if gulity personally he went by car. I think his adrenalin would have been pumping after the massacre and he would want a swift exit. It could explain that he drove out to dispose of his murder clothes that were never found or discovered in any event?.
A car although riskier, is a quicker option. He could if gulity just have got lucky in the aspect.
Head street in goldhanger is sleepy. At that time the vast majority of people in the midweek, especially in 1985 would have been fast on asleep in bed. The journey to WHF gets even sleepier.
He could have done it by car easy IMO