§ Mr. Skeetasked the Secreetary of State for the Environment what is the efficiency of the internal combustion engine with and without lead additives.
§ Mr. Kenneth ClarkeI have been asked to reply.Lead additives increase octane ratings so permitting the use of higher compression ratio engines and ensuring higher fuel efficiency.
Typical current model cars designed to run on four star leaded petrol use fuel about 6 per cent. more efficiently than similar models with engines designed to run on lower octane lead free petrol.