Does anyone remember what the episode is called?

I used to watch a ton of episodes as a kid. Some were quite scary, some not quite scary.

I remember this one episode where the gang was solving a mystery involving a vampire and something like it. Unknown to the gang, he was on the roof of the Mystery Machine and after some time, he popped his head over the windscreen.

The gang screamed in fright and I think Fred crashed the vehicle (I forgot because it's been so long.