This essay might reframe naming, http://paulgraham.com/name.html
Unless you specifically want to include "carpool" as a keyword, I'd say the name you have seems as good as any...
Poolwith me sounds pretty good. Personally, I think 'ridewith.me' rolls off the tongue slightly better. Nonetheless good luck.
ideas: Poolber, RouteScrum, EventuArrive, RideOrgy, Menage-A-Trip.
I like the name you already have. You should keep it.
It's a good name. Don't sweat it.
Alternatively grab a German dictionary.