Exactly this happened to my father last fall with a Audi Q1. It finally turned out to be a electronics issue, but the car was limiting itself to very low max speeds (40 kmh or so, which legally disallowed my father from using the Autobahn).

With a car the obvious answer is: get the thing checked immidiately. He did, and he still had to drive around like this for 2 weeks till a replacement part arrived.