I remember watching this series as a kid. The protagonists were two teenagers - a boy and a girl. They had a VW Bus in their backyard, with some kind of satellite dish on top of it. It had something to do with space travel or time travel, I think (or communicating with someone in space?) I cannot remember many details, except for one episode, which revolved around barrels containing some radioactive materials, and a pesky neighbour (who I think appeared in all episodes, though I don't remember that well).
It definitely isn't Mystery Science Theater 3000, I know there was a VW Bus with a satellite dish there, but that's a completely different series. Also, I'm pretty sure it wasn't American - most probably British.