I've also had a couple of not so great experiences with Europcar.

First time: ex-Monte Carlo they charged the security deposit of 1000 euros to my AmEx card - it should have only been an authorisation. Of course I did not find this out until I returned home and received my AmEx statement - it took 6+ months to recover this money - I lost over $100 on exchange rate variations.

Second time: picked up car in Marseilles - took at least one hour to complete paper work; then upon going to collect the car in the lot (10 minutes walk from the office) - I find the car is one grade lower than I had booked and paid for. Even worse it was filthy - reeked of cigaret smoke - even the ash-tray was full of butts. Ugh - because of lengthy time it took to just complete the paper work and the long walk to the lot - I kept the car - but never again.

All that being said - on both occasions - Europcar was considerably cheaper than the Avis, Hertz, ....