BMW has announced a limited edition homologation version of the 3-series powered by a hand-built, high-revving four-cylinder engine.
The £25,000 320Si has been manufactured to meet FIA homologation regulations for the 2006 BMW World Touring Car. Just 2600 will be built for sale worldwide and 500 of those will be offered in the UK.
The engine delivers 175bhp and 148lb ft of torque – 25bhp and 1lb ft more than a 320i - and redlines at 7300rpm. The 0-62mph time is a modest 8.1sec (1.2sec faster) and it reaches a 10mph faster maximum of 140mph.
BMW says the 2.0-litre engine will be hand-built at its Hams Hall engine plant near Coventry. Significantly modified, it uses bigger inlet and outlet valves, a higher compression ratio (10.5:1 to 11.0:1) and the pistons now run in aluminium-alloy liners.
The cylinder bore has been increased by 1mm to 85mm and the stroke reduced by 2mm to 88mm. The engine also uses a conventional throttle system in place of BMW’s valvetronic induction set-up. The cylinder head is cast at its Landshut foundry alongside F1 cylinder blocks. The carbon fibre engine cover is said to save 10kgs of weight in the nose.