The JCB Dieselmax is a streamliner car designed for the purpose of breaking the land speed record for a diesel-engined vehicle.

As of 2018, the car holds the world diesel-powered land speed record, having been driven to over 350 miles per hour (560 km/h) by Wing Commander Andy Green in 2006.

[1] The car is powered by two specially-tuned versions of the production JCB444[2] powerplant, developing up to 750 brake horsepower (560 kW) each (over five times the power output of the production version with 90 psi (6 bar) of boost) and featuring four cylinders and 5 litres of displacement, accompanied by two stage turbochargers, intercooler and aftercooler.

The fully laden weight of the vehicle, including fuel, oil, ice, water coolant and the driver, is slightly less than 2,700 kg.

24 hours later the JCB Dieselmax car broke its own record, achieving a speed of 350.092 mph (563.418 km/h) over a distance of 1 mile on 23 August 2006.