Fastest ever? Maybe.
An old guy nearby had a "tree harvester" he'd built out of a surplus GM military prototype chassis. It was 6x6, 4-wheel steer, and (from what he claimed) originally had 48" tires and was powered by a Lycoming helicopter engine. He said the army claimed a 0-60mph of around 6 seconds. Maybe not as fast at the Devel, but Devel doesn't seem to advertise a 0-60 time, so who knows?
FWIW: The tree harvester was powered by a small v-8, coupled through three transmissions inline, and smaller dia. tires, so it went pretty slow. It had an old Chicago firetruck cab fitted with hydraulic steering, a huge dump bed with two winches at the front - one small aircraft cable winch and a larger tank-retrieval winch, and a giant roll-bar thing over the tailgate. He'd back the truck to a woods, pull the small cable out to a snatch-block on a tree and use that to pull out the main cable. Then he'd fell the tree, grab it with the winch, and pull it through the roll-bar, crushing the limbs in. He'd cut it up on the truck, as the bed had a central strip of planks surrounded by enormous woven wire panels, and the sawdust just fell through. When he was done, he'd dump the load in his yard.
I can't vouch for his performance claims about the original prototype, but I actually saw the tree harvester.