A risk with the car is the off chance a passing police car decides to pull it due to the unsociable hours. The police may suspect that the driver is out burgling.
If he was stopped on the return journey, he's fucked. The same goes for cycling, any passing police car would view a guy cycling the roads at 2am suspicious and think he was out doing some kind of skullduggery.
Bews remarked that Bambers car was the only vehicle they saw on the way to WHF, a testament to how quiet the roads were at that hour(s)