For MAD you would want to rent a car because it gives you access to many easily accessible spots.[/quote]
Yes I would also prefer a car BUT last year I did it without a car. You only need a good taxidriver. I had so much luck that I got one who spoke germen as well cause my spanish isn't very well and not all taxidriver speaks good english.
For example one day we used the shuttle bus and than we walked to the spotting places (aprox 30min) so its even better to have a car but it is not impossible to spot without it.