The replacement to the turbocharged 4.7-litre V8 in the outgoing models, the new 3.0-litre twin-turbo unit offers 330bhp, putting it between Mercedes' existing 3.5-litre single-turbo V6, which develops 303bhp, and the 404bhp of the outgoing V8.

The twin-turbo engine has been tuned to fit the needs of a touring coupé or convertible and delivers 354lb.ft between 1,400rpm and 4,000rpm.

It also offers significant improvements in fuel economy and emissions. The official fuel consumption and CO2 emissions of the E400 Coupé are 37.2mpg and 177g/km, while for the heavier Cabriolet they are 35.8mpg and 185g/km. These are improvements of up to 5.5mpg and 32g/km over the figures for the V8 models.

Mercedes describes the 3.0-litre V6 engine as "all-new, but with some parts from the 3.5-litre V6". The original plan was to add a second turbo to the 3.5-litre unit, but Mercedes discovered it could get the performance it wanted with greater efficiency from a smaller-capacity twin-turbo engine.

The 3.5-litre engine will remain in production for customers in other markets who want V6 power at a lower cost, while the V8 remains an additional offering outside the UK.

Mercedes said there are no plans to fit the twin-turbo engine to UK versions of the E-Class saloon and estate, which are sold primarily with diesel engines, but that the decision could be revised if there is demand.