There are ordinary semi trucks and then there is Thor24. The machine never appeared in any brochure because it began as a fully bespoke build based on the extended frame of a 1979 Peterbilt 359. Power comes from a one-of-a-kind V24 created by joining two retired Detroit Diesel V12 two-stroke engines with a splined crankshaft and feeding them through twelve superchargers to produce almost 4,000 horsepower.

The 44-foot-long, 32,000-pound vehicle can reach 130 mph, a figure that required years of careful engineering. Builder Mike Harrah devoted seven years and roughly seven million dollars to the project. In 2019 the truck crossed the block at a Worldwide Auctioneers sale in Riyadh and brought a record twelve million dollars, making it the most expensive semi truck ever sold. Despite the location of the auction, the vehicle stayed in Arizona where it was constructed.

The engineering behind Thor24

Harrah started with two 13.9-liter Detroit Diesel V12 engines that originally produced about 475 horsepower each. He joined them end to end with a splined crankshaft to create a 27.9-liter V24 that drives an Allison HT740 transmission. Twelve Detroit 6-71 superchargers and eight nitrous-oxide bottles mounted between the cylinder banks complete the forced-induction package, resulting in a claimed output of 3,974 horsepower.

Even at 32,000 pounds the truck can reach 130 mph. Four twelve-foot drag parachutes help bring it to a stop. The underside features extensive chrome plating, polished aluminum, and stainless-steel components that match the rest of the build.

Thor24 usability supports its high value

Value does not come only from horsepower or polished components. The original Peterbilt cab was lengthened to add an extra pair of doors, and the passenger door operates in scissor fashion like a Lamborghini. Inside, twenty-four gauges surround a custom broadsword-style shifter. Seven video screens and a 1,500-watt-per-channel 110-volt sound system provide entertainment, yet the truck retains full trailer-towing capability. That combination of extreme customization and genuine usability explains the eight-figure auction price.