Andrew,
You may have just opened a pandora's box, mano, but here goes.... The tractor is a 1/4 scale about 8ft long by 5 ft wide according to regulations. We are given a 16 hp Briggs and Stratton motor, which cannot have any more modifications than exhaust and oil changes, and tires, which we must use, but can cut to a tread pattern of our desire. Drive system is where it gets complicated. The orange tractor you saw on the site utilized a hydro-mechanical, stepless transmission. Basically it behaves like an automatic transmission that does not have shift points because there is only one gear, but the gear ratio can change, if that makes any sense at all. What this does is allow us to "shift" from high gear (about .80:1, or a common overdrive) to low gear (technically, it shouldn't go below 3:1 under without breaking the planetary gear or drive shafts, but we once had it below 100:1, yes below 100:1 without snapping anything when we weighed 3000lbs, and down to infinite:1 without load) without the engine ever leaving 3100 rpm, or peak horsepower, and pull about 80% efficiency. We attempted to patent this transmission, however intellectual properties here on campus significantly reduced their services and funding ran short, so we did not, even though we did basically have the go ahead. Beyond the transmission, its stepped about another 50:1 before heading to the tires, where top speed is about 10mph, and basically no lowest speed. It is four wheel drive, and the tractor, without driver but with fluids and all components, cannot weigh over 850lbs and is pulled in 1000, 1250, 1500, and 1750 lb classes. The sled we pull weighs about 6000lbs. It has some extreme bells and whistles and in the end the finished product cost about $10000 to $15000 for parts, and about 1800 man hours worth of labor, a great portion of which is welding and is ALL mine. This, of course, translated into a production model, would be around $3500 worth of parts and labor total, showing just how handmade this thing is.
The competition is inter-collegiate(28 total this last year) and international, including several Canadian colleges, in the past has involved a Malaysian college, and we have heard rumors of an Ireland college having interest. All that said, we brought home the championship with the orange one you saw.
I could go on, but a lot of info can be found on
www.ASAE.org
if you are more interested in rules and stuff. If you want to know more, just ask, I've been involved in it the last 4 yrs.
G. L.
Watch out if you plan to use an old 55 gal. drum, it may have had something in it that would have dangerous fumes cooking into your food. Just because it looks clean or has had a fire in it already doesn't mean it's fit to be used as a cooker. 
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