What is the current price of gas or diesel in Spain I am making plans for a rental car and trying to decide whether to make the longer trips by public transportatiom or drive

Fuel has shot up in price over the last 6 months and diesel has now overtaken petrol (gas in US English?).

Expect to pay around 1,20 € per litre of diesel, and 1,15 € per litre of petrol.

Don't forget to take into account the motorway tolls too, btw.

If you're doing driving trips around Madrid than tolls will be no more than 7 euros, on longer trips it's surprisingly easy to skip the toll roads. Where are you thinking of going?

Also if you do rent a car request a diesel as it gets better "gas" mileage