Re: diesel ATV\'s?
They don't like cold weather too much, and they are underpowered. They weigh about 60 pounds more than a standard Polaris Sportsman 500 H.O., which feels like it makes twice the power. That, and there is the aweful "is a piston about to shoot through my leg?" noise that they make. I know diesels are noisy, but that noise between your legs is downright frightning. They have since dropped the Diesel quad from their lineup, basically because it sucked. Good idea on paper, not so good in the real world.
I would stick with a more "normal" quad. My favorite utility quad is the Sportsman 500 H.O. . They ride nice, have plenty of power, and are pretty fun when pushed, even for a big utility quad. The 700 Twin is too heavy, and the 400 feels like it has about 1/2 the power (and is that way in drag runs and hill climbs too). To me Yamaha's Grizzly is just a lot less of a joy to ride. Works great, but isn't as fun to play with.
By the way, I am probably way biased cause I work at a Polaris dealership. The above is my honest opinions though.
85 SR5, hey that rhymes!