Other Car Rental Programs (ie. Alamo, Enterprise) - Five weeks in Spain - best options?

I'm in Spain for five weeks and need a car and been shopping around and prices vary dramatically...

Can you recommend the best options available?

Best price I found was £502 for the five weeks (23rd Aug to 29th Sep) but I'm sure it can be bettered

Have you thought about leasing the car? When I lived in Italy for 6 weeks I basically got a lease on a car...as if I were getting a permanent car. In many countries in Europe you can back out of a lease within 6 months with no penalty.

So, I basically put 3k down as a refundable down payment, paid the monthly lease of about 235 dollars, and returned the car/lease when it was over, getting my 3k back, having only paid 260 for the 6 weeks. Apparently it's done all the time and is the preferred method for those in the EU who plan to stay a month or more.

I was looking at these options which I see are abaliable to US residents in the Eu but it was working out to be way more expensive than renting.

I finally got a Megane equivalent for £496