Good brainstorm over a beer with my buddies on the Germanness of America, some of which I already mentioned:
1. TV advertising (slapstick, not subtle)
2. The Army (are there more German generals than German politicians in the US -- which states does army recruit from?)
Pershing, Eisenhower, Schwartzkopf
3. Attitude to self improvement
The German poet Rilke's mantra "You must change your life" caught on a lot faster in America, especially California, than Britain. For example, my Swiss German paternal grandfather was a health food nut who moved to Southern California 85 years ago to grow his own food in his yard.
4. Easy to scare (see Hollywood), lack of natural scepticism
5. Taking things serious (the brit needs to be seen not to be trying)
6. Lack of irony
7. American English -- tendency to use longer words eg. Transportation rather than Transport, tendency to use "The" ie. "The Congress" rather than just "Congress"
8. Law abidingness eg. attitude to jaywalking