Well, i know you guys do not have the possibility to buy a ISUZU, but just for the heck of it.....
Just did the math on the mileage....
While towing the 5.0 Classic from the Netherlands (flat land) via Germany and Switzerland (both uphill/mountains) to Tuscany (mountains) we did 11.5Km to the liter, that is about....
7.14 mile per liter which would be about 7.14 * 3.7 = 26.4 miles to the gallon if i'm not mistaken.
we drive about 85-90 km's/H or 52-55 miles/H. Which is the legal max speed in Europe when towing.
Not too bad at all i believe, this is achieved with a 2.5Litre twin turbo diesel engine.
Uphill we experienced no problems at all, maintaining our 90Km/H speed was easy, just clicked the cruise control to 90 and up we went. Ref's were standard about 1300-1500 RPM's and uphill about 2000 RPM's.
Just to let you know.
Severinus and Yvonne