I don't know whether or not "Hoch auf dem gelben Wagen" would be considered a folksong by the purists. It was written by Rudolf Baumbach (lyrics) and Heinz Höhne in 1923. The song is certainly very well known and I recall a prominent German politician sometime in the 1970's singing it on TV no doubt to prove how close ("volksnah") he was to the voters. The version I sing can be found in Lieder, Songs und Gospels 1
The song itself is quite jolly ditty about an outing in a yellow cart into the beauties of the countryside. Underway, the singer sees all many kinds of attractions such as dancing, drinking etc. but is obliged to remain onboard the yellow wagon because it keeps rolling along without stopping.