I used a 2wd 318 95 ram sport to haul a dodge stealth twin turbo which weighs 3900lbs on a 2000lbs trailer plus I had 2 engines in the bed. There was also much more in the car/bed, easily 7000 lbs. From Detroit to sw PA. I had no problem at all and actually got around 11mpgs, it was flat and all highway.

I'm sure the mpg's are going to be bad though with the enclosed trailer!