The film you are likely thinking of is "Die lustigen Vier von der Tankstelle" (The Funny Four from the Gas Station), which was released in 1966. It starred:
* Heinz Erhardt as Paul "Paule" Pfeiffer
* Liselotte Pulver as Susi
* Wolfgang Völz as "Schnappi" Schneider
* Germaine Damar as Aunt Emilie
* Peter Weck as Herbert "Herb" Meier
There were two sequels to this movie:
* Die lustigen Vier auf der Autobahn (1970)
* Die lustigen Vier im Mai (1971)
Both sequels starred the same core cast, though there might be some changes in supporting roles.
Did you perhaps misremember the year of the film?