The smaller "Garden Tractors" have taken off in the last 5 or so years. The advantages are :
1) they are small and light enough to be towed on a 6x4 trailer
2) easily towed by a standard car
3) don't need much storage space - can fit 3 to 4 in the space needed to store a grey fergie
4) easily maneuvered around a rally ground
5) almost impossible to bog
6) makes a good looking load on a historic truck filling the tray without much weight or wind resistance
disadvantages:
1) almost impossible to register - even on a club permit
2) tractive effort depends on the weight of the driver - the heavier the driver the more grip you have.
3) flat out at around 4 to 7 miles per hour depending on the model (which is why they are hard to register (at least in Victoria)
I wanted to register/ put cps on my Howard 2000 as I live less than a km from the steam rally ground/truck show ground in Echuca and could drive it there on side roads faster than loading it onto a vehicle and tying it on.
the photo is taken at Old Tailem Town on the way to the 2009 NHMA National Rally at Murray Bridge. We were away for 10 days that trip and did some sight seeing around the Adelaide Hills etc while we were there