Car makers' apps - just a gimmick or actually useful?

Most car manufacturers now offer apps that can be used to control many of your car's functions. But are they really a useful addition to the vehicle? — dpa

Set your next day's driving route on your smartphone from the sofa, send it to your car's navigation system and tomorrow morning you're ready to go.

That's one common use for the apps offered by car manufacturers to accompany their vehicles. But are they good for anything else?