We are planning to rent a car in Spain and take it into Portugal. We are traveling Sept 22 - 28, 2013. do you know of a car rental agency that:
a) will let us pick up on a Sunday (Seville, Spain)
b) drop off 7 days later (Saturday) in Lisbon, Portugal
and not charge an exhorbitant one-way /transfer fee?
Thanks!

You might be lucky and find a car with Portuguese plates in Seville. Otherwise count on a drop off fee.

Try Economyrentals or AutoEurope

If you do pick up a car in Sevilla and drop it off in Lisbon, there is a one-way fee as well as a fee for picking up in one country and dropping off in another. Note that not all rentals cars can be dropped off in a second country.

The easy solution is to take the bus from Sevilla to Portugal and pick up the rental car there once you cross the border.

Now days some hire companies do not even allow you to take the car across the border without an extra charge, so drop off fees are the norm.

Within a country, one-way fees are not always applied. http://www.economycarrentals.com/ has them, but Autoeurope and Kemwel do not; and taking the car across the border is not a problem unless certain restrictions apply (can a French rental be taken to Italy if the CDW is declined?) or the rental agency specifies that a car cannot be taken to eastern European countries. But cross-border drop-off fees are generally applied.

Yes, Auto Europe and Kemwel do charge one-way drop off fees (it's not them, but the actual rental car rental agency - AVIS, Hertz, Europcar, etc). AE is only the broker.

With a trip like this, you will have to use the large hire companies,as smaller/regional companies probably won't allow such a request. You will therefore have to pay the appropriate fees for dropping the car off in another country.

Try shopping around for the cheapest price, but it will be expensive. Robert's suggestion to rent once you get into Portugal is probably the best on an economic level, otherwise you'll have to swallow hard and pay the fess.

<i>Auto Europe and Kemwel do charge one-way drop off fees (it's not them, but the actual rental car rental agency - AVIS, Hertz, Europcar, etc). AE is only the broker.</i>

Europcar did not charge me one way fees any time I've rented from them, including a trip in Portugal, taking the car to Spain and returning it at a different location in Portugal. I've tried to check, and I see no evidence that rates through Autoeurope for Europcar rentals are any higher than if renting from Hertz.

I don't know how often you rent cars in Europe, but there is always a fee when picking up in one location and dropping off in another, read your contract carefully. The drop off fee may be included in the total cost of the rental, depending on which agency is providing the car. They are all different.

Picking up in one country and dropping off in a second country always incurs a fee, regardless of the rental agency. There is also a fee (city tax) for picking up at an airport or train station, rates vary depending on the location and type of vehicle.

Here are the typical notes associated with a rental in Galicia through AE:

Your rental excludes:
Location Surcharge of approximately EUR 48.30 EUR for rentals commencing at an airport or approx. EUR 18.45 to EUR 24.80 EUR at a rail station location.

Domestic One Way fee of approximately EUR 60.50.

Local toll, highway fees or travel stickers which may be required by local authorities

<i>I don't know how often you rent cars in Europe, but there is always a fee when picking up in one location and dropping off in another, read your contract carefully. The drop off fee may be included in the total cost of the rental, depending on which agency is providing the car.</i>

I am careful and have previously pointed out that the train station fee levied by Europcar is cheaper than the one-way fee levied by Hertz (half the cost). In Norway Kemwel offered a cheaper rate than Autoeurope until it turned out that Kemwel's rental agency levied a one-way fee that did not exist with Autoeurope's rental agency. One may argue that the higher base rate reflects a one-way fee, but that fee is less than the added fee from other agencies.

I rented three different cars this past summer, in Germany, France, and England; and I usually rent at least two different cars every summer for the past 12 years or so.