The project involves rebuilding former London Underground D78 metro cars rendered surplus by the introduction of new Bombardier trains on the District Line.
The only major components of the D78 to be retained in the D-Train are the aluminium bodyshell, bogies, traction motors and rheostatic braking system.
"This is effectively a new train made affordable by reusing a corrosion-free body and bogies that are only 8-10 years old," says Vivarail chairman Mr Adrian Shooter. "If we didn't have an excellent bodyshell and bogies we wouldn't have embarked on this."
Each driving motor vehicle is equipped with an engine raft housing two 3.2 litre five-cylinder Ford diesel engines, each with a nominal output of 149kW, or 596kW for a two or three-car set.
The D-Train will be offered in a variety of suburban and regional configurations, and is intended to address the shortage of DMUs in the British market.
Vivarail aims to begin mainline testing in October with the prototype three-car train, initially on the Moreton-in-Marsh - Honeybourne section of the Oxford - Worcester line, which passes the company's Long Marston base. A passenger trial with a franchised train operator will take place early next year.
A full description of the D-Train project is available here.