Using a minivan may not be for everybody, but it has its place. Here's what I've seen for MPG with my first year having the '07 3.9 Uplander LS but about 500 pounds gear. All average traveling speed 72 to 75 mph
499 miles, VIR to oh w/o trailer 23 gal 21.69 mpg
446 miles, OH to Wis w/o trailer , 19.2 gal 23.2 mpg
660 miles, wis to OH w/o trailer , 32.75 gal 20.15 mpg

I don't log mpg on my race weekends in wisconsin when I am towing (Cause its less than a full tank) but its 16.5 to 17 mpg pretty consistently, running about 72. I have never seen less than 16 mpg and have seen nearly 18 mpg (note - headwinds will make a +/- 1.5 ppg difference). A nice thing is the 25 gallon tank makes really great range

For a 3500 pound open trailer including car, the uplander handling is fine assuming you add the air springs, kyb rear shocks and have 400 to 500 pounds tongue weight. Its pretty nimble, no drama, my wife enjoys the ride. Its an option to anybody who has an 2500 pound IT car and open trailer but doesn't want to put a $$ into a dedicated pickup truck or V8 van, and also wants to get utilty out of it for the rest of the year. Understand, I am speaking of the 3.9 '07 - '08 Uplander, I don't think the earlier 3.4 engines are good for towing, or even got as good as gas mileage.

Also, I am speaking of the Uplander with the beam rear axle, 3.9 engine, and 6 bolt heavy duty brakes. I would avoid the earlier models with 5 bolt brakes, the 3.4 engine, or any Montana, Terraza or Saturn with independent rear suspension minivans unless you have tested it towing. For one thing, the shocks and air springs I found won't work on a independent rear and I think they are really needed to keep things buttened down.

Along those lines, I did look at a '05 Honda Oddysey with factory towing package and found it scary. If you twitched the wheel on a fast lane change, the rear suspension just wouldn't take a set. Another disadvantage with the Odysey is that with a 5 speed transmission, I couldn't prevent it from shifting out of 5th at over 70 when towing. It seems the GM 4 speed and 3.9 motor makes a better towing package.

Anyway, for those who don't live in mountains and who have a 3500 pound trailer. I think the '07 - '08 Uplander is worth a look because it tows well and serves as a dual duty vehicle. I already have 4,000 miles towing on it and can recommend it.