I'm booking a car at Barcelona el Prat, and Interrent gives me a rate of 3.91 euro for 2 days, excluding fuel.
Can that be right? I only need it to get to a hotel and back.
Has anyone used this firm?

Autoeurope gives me a rate of 33 euro for the same firm, same dates.

no, that can't be right. If this is the cheapest car they have, I think you could get it for about 30 euro for two days, but not 4 euro. The cheapest rate I see on their website is 16 euro a day for some off periods a couple months away.

what dates are you looking at?

I have to think there's a misplaced period (comma) in that price. OTOH if it's one of those instances in which a company mistakenly advertises a ridiculous price (which happens with airlines sometimes), grab it - what do you have to lose?

"InterRent is the new international car rental low cost brand from the Europcar group". The cost of a SEAT Mini on a one-day rental, Express Fuel Option, is 24,10€ / day* Not to say I wouldn't trust them (Europcar has been getting some bad reviews in Portugal), but you have to read the conditions (below) to get the full story of the rental.

• Pick-up the car with a full tank.
  Fuel is not included in the price displayed, it will be charged on pick-up with a non-refundable Express service fee. *Estimated cost (depending on the capacity of the tank) will be of 80 - 101€
  Consult our fuel policy
• You may return the car without refueling to save time. You will be refunded for any unused fuel.
• Free cancellation is possible up to 2 hours before pick-up!
  

Go with Auto Europe. They are a great company located in Portland, Maine. If you purchase full coverage insurance, prepay with them. They are a broker and have great rates with Hertz, which charges a lot more for insurance if you book through them. We have four rentals with them this fall in different places, all one way, and all very reasonable.

Our son rented a car in eastern Europe through a European agency. They upgraded him to a sports car; it broke down with 15 minutes. Six months later, they hit his credit card for $4,500 for motor damage (nothing to do with him), and it took him a year or more to get the charge removed. Stick with a US-based company.

This is what I get for 2 days, Wednesday/Thursday in June.
The premium package including insurance will bring it to about 30/day, but I have a comprehensive travel insurance including car rental.

From the Daily Mail 4/27/2018:
"InterRent has been named as the worst car hire firm in an annual consumer survey, with customers complaining about the standard of its cars and the attitude of staff.

The poll, by Which? Travel, saw the newcomer knock Goldcar from the bottom spot for the first time in five years – with the lowest score that's ever been registered.

Customers of budget firm InterRent told the consumer rights group that they had been subjected to filthy vehicles, lengthy queues, pushy sales staff and unexpected charges, provoking a poor customer score of just 31 per cent."

As the saying goes: If it's too good to be true, then it probably is.

"Not to say I wouldn't trust them". I wouldn't!

If your hotel is in the city, take a taxi. It's around 30€ to the center of the city. No parking charges, no fuel charges, and no hassle. And no driving in Barcelona's traffic!

https://www.interrent.com/about-us

<<We are incredibly easy to sue >>

LOL, I think that's a tip off.

That did not take long for someone to pick up on the error. Well spotted Christina. 10 points.

Indeed! May be too much hassle. I'm not staying in town, but near the university.
I see now that there is a direct metro line - I'll probably do that.

Thanks for your input!

I believe that Autoeurope has a three day minimum rental policy.

No you can rent for a day through Autoeurope.
I don't really see why, as a European, I should stick with a US-based company, though...

I saw the above suggestion about this company and thought WTF. Perhaps you should use New York City Transit Authority for the metro!

you do NOT want a car IN Barcelona. Taxis and airport bus and then taxi from Plaza Cataluña is easiest way. Then taxis or Cabify within the city ( if Barcelona still has this new Uber competitive taxi group).

Parking is outrageously expensive and the stress of getting around such a congested city does not make for a pleasant outing.

I'm not in Barcelona, but I have since discovered that there is a good metro connection to my destination.