I've been looking at car rentals with a pickup and return in Lisbon. We plan to drive into Spain for a couple days. Several car rental companies have asked about taking the car into a country other than Portugal. They add a hefty fee for a "card" to take the car into Spain. I have driven many rental cars cross borders and never had to pay an additional fee. Is this something new in Europe or is it specific to Portugal or Spain?

Who are you dealing with? Since you're from the States, there is no such requirement if dealing with brokers like Auto Europe and Kemwel, nor with Avis, Hertz or EuropCar. If you're dealing with a local Portuguese company, then they may have their own requirements, but it's not something I've ever encountered when going from Portugal to Spain or in the reverse, which we do quite often.

Thanks, that's good to know. I did look at Hertz, Kemwell and Auto Europe and didn't notice this addition. The site I was on was another consolidator site called ecorentals or something to that effect.

If you were dropping off the car in Spain, there could be a large fee.

I am not dropping the car off in Spain. Its a roundtrip rental from Lisbon.

You will certainly have to read the T&Cs some smaller companies do charge to take the car into Spain. There is an extra charge for breakdown cover.
Also some hire companies do not include the electronic tag required for some Portuguese toll roads. It is law to provide them but some just do not. Again read the T&Cs to make sure it is included.

Using carrentals.com we were placed with Sixt and had no fees for crossing into Spain and back.

I did confirm with Sixt by e-mail that there would be no extra charges.

But this was two years ago.

Don't forget your IDP, an International Driving Permit.

We did get stopped by the police in Portugal and they looked at both my US license and the IDP.

I do not even understand crossing fees, as there is no way to verify this.

And you do not need an IDP unless you are stopped and then the police can be nasty.

Is there some possibility that if this is a small local company they may have insurance only in Portugal - and charge extra if you take it out of the country?

(We've never run into this but always use major companies - which have sometimes - but not always - charged for drop off in another country - never just to drive into one.)