I just applied for a Sixt Card and was intrigued by their dual track for status. If you rent more than 5 times in a year, you will get upgraded to Gold. If you rent more than 20 times a year, you will be given Platinum.

BUT...and this is the interesting part...most F/Ters can get one of these cards immediately -- based on their status with their airline or hotel chain.

For Gold, you need minimum elite status (Silver Medallion with Delta, Hilton Gold, etc). With some airlines, like El Al or Lufthansa, simply being a member is enough.

For Platinum, you need a higher level. OnePass Gold or Hilton Diamond will suffice.

I don't know how carefully they check. Last year I was Gold with Delta and went down to Silver this year. I decided to give myself the benefit of the doubt, applied for Platinum, and said I was Delta Gold. When I finished filling out the form, I was told that my application would be reviewed and that I would be sent either the Platinum Card or the proper card to which I am entitled.

(In other words, if they contact Delta, I will be sent the Gold.)

Generally I rent with Hertz, but I think that in Europe -- especially in Germany -- Sixt may be the better deal.