"Oh, derby, that's another good synonym," Walter says eagerly, always eager to come up with silly little nicknames and so on. To be more serious...

"For a long time it's been on my mind that vehicles can differ from era to era, or even be unprecedented for some. Not to mention that automobile accidents are one of the leading causes of premature deaths such as those that have led inmates to the barge. Then I considered it more after the last port - how there was a lot of driving involved." He shrugs thoughtfully. "And the enclosure could be used to simulate something outright dangerous. You could try to weave in and out of rival gang members as you jockey for first to smuggle the goods to the other side of town..."