everyone keeps talking here about making reservations ahead of time, but honestly, national car rental is the cheapest and we got the same rate from walking upstairs to the office the day before we left. it was a three day rental so it was more expensive per day than a 2 week rental would have been. my advice is this - take the metro to plaza de espana, cross the street and walk up the stairs .

Billings, I always reserve on-line in the US (which often means having to place a 800-phone call as well) with Avis. Costs about $110-120 for 10-14 days - unlimited mileage.
Always an Opel stick-shift; pick-up in Madrid. Translating pesetas is a few mposts prior - and acknowledging the rental car was larger than what I get ... three days for almost the same price as for 12 days - suggest you at least do some homework on the internet. Please do take into consideration that I travel first three months of the year and that might have some bearing on the costs.

And what about AAA (Automobile Association of America) discounts? I would assume we here in the USA could only get these discounts booking from here as opposed to trying to get the same discount in Spain since AAA doesn't exist there even though the 'American' rental companies do.

Saludos, MadridMan