The only thing that keeps it moving is the poor bastard stuck in it. This is an experience to cause problems in the most stable personalities. Which brings me to the second point. As soon as the sun edges the horizon, boom, out like a light. Oh, sure, if you really exert yourself, you might stay up for 10 or 15 minutes, but it leaves you drained for at least the next week.
Vampires are slightly more combustible than lighter fluid.
And harder to put out too. Something to do with drying out and not decomposing. And there's one or two other things too. Like haven't eaten in the last two days. Then you know how hungry a vampire is right after feeding.