This post on FatWallet.com looks like it can save me a ton on a car rental.

Using europecar, I was quoted 267.51 EUR for my rental (economy car) from the 3rd to the 7th. The fatwallet post directed me to try booking at lastminute.com which seems to be a european travel site. I got quoted £90.00 for the same class of car (through Hertz)!!!

This is a fantastic savings! The only snag seems to be that you have to enter a European phone number to book the car. So, who will be willing to lend me their phone number.