in Germany when you are under 25. :~) I called Avis and those idiots charge you an extra Euro 9.85/day for seven days[whether u rent for 1 day or 7]; if you are under 25. And Hertz don’t even risk having 25- ppl behind the wheels: LOSERS!!! They don’t care if you have a clean record in the U.S. or not.
Would it be a good idea to show up at their office [at the frankfurt airport] and then hope that somehow they won’t notice you are below 25. 
any ideas??
I know Germans can be idiots at times buI am sure they'll ask for some form of identification before giving you the car keys. So, hoping they won't notice is a bit...umm....whats the word I am looking for...idiotic?
ofcourse they will ask for id; intl drivers license and us license. they are not canadians. to believe that they won't do that is hmmm a bit idiotic i think.
there could be a slight chance that they might overlook the age field. unless they ask me: ARE U 25 or older?
Tried that trick myself and believe me they will ask you how old you are several times as well as the fact that its going to be blatantely obvious when they see your i.d.
Just pay the extra.
well i only had to pay 140 euro for 3 days including all types of necessary insurance(for a compact car) with unlimited mileage. and had a different return location. this seems like a very good deal. she didn't charge me anything for not being 25. actually she didn't even ask.
its best to get the car when you arrive at the airport. getting fares from various car rental companies at the airport gives you more options and lets them know that you are for real.
it was interesting to note that the lady said atleast 10 times that 'sorry sir we don't have very big cars over here. it is not like states' :D
its fun to drive on autobahn :D
Next time give EUROPCAR a try since they r cheaper than AVIS + a lot more friendly than AVIS