BMW is introducing three new six-cylinder engines for its top-selling 3 series range from September.

These are a 306hp twin-turbo three-litre petrol engine, to be badged 335i, and a 197hp single turbocharger diesel called the 325d. Also coming are twin-turbocharged 2,993cc diesel models with 286hp badged 335d.

The 325d accelerates from rest to 62mph (100km/h) in 7.4-7.6 seconds depending on boy style, has a top speed speed of 145-146mph and 'official' EC CO2 emissions of 171-176g/km. The twin turbo 335d does the 62mph sprint in 6.1-6.3sec, is governed to a top speed of 155mph and has CO2 emissions of 200-205g/km.

The range-topping twin-turbo petrol 335i despatches 62mph in 5.6-5.7sec, is also governed to 155mph top speed and emits 231-235g of CO2 per kilometre.