Cheap car rentals in Portugal?!

So, something has come up and I am so lucky. I am getting the chance to go back to Portugal for six weeks. However, I need to rent a car. I understand it is peak season, but, wow, I simply cannot afford it. Does anyone have any suggestions for the best cheap rental? I have looked at National, Budget, Thrifty, Europecar, Expedia, Kayak .... All of the sites. 

There used to be something called rent-a-wreck but all of those sites are a little curious...

If you have any tips please let me know!

Maybe I'll rent a bike and a trailer... Or....

Pippa