Lamborghini could be on the verge of a revolutionary supercar step. The Italian firm is testing a diesel Gallardo, with power coming from the 5.0-litre 309bhp V10 VW engine. According to our sources, Lamborghini engineers are happy with the performance, especially the staggering 553lb ft of torque, but the problem lies with the power delivery, in part due to the narrow rev-range characteristics of a diesel engine. Lamborghini is not the only company to look into an alternative fuel for a supercar. Toyota has a running prototype for a petrol-electric hybrid supercar, with a view to a launch in 2007.