A new range of more powerful, torquier and more frugal V6 and V8 petrol engines will be introduced across the Mercedes range from autumn this year.
The headline changes for the V6 are a new narrow-angle block and for the V8 a reduction in capacity mated to twin-turbo induction.
Both vee-engines also get third-generation direct injection with piezo-electric injectors, revised combustion, multi-spark ignition and low-friction ancillaries to cut fuel consumption by up to 24 per cent.
Major changes are wrought to the V8, which gets a new, smaller-capacity block of 4.6 litres, reduced by 15 per cent from the 5.4 litres of its predecessor, together with the addition of twin turbochargers, arranged with one blower for each bank of cylinders.
Peak power goes up to 429bhp, a 12 per increase, while torque is boosted 32 per cent to a whopping 516lb ft.
“The driver experiences the same pleasant and effortless performance from the new V8 as that delivered by a mighty, naturally aspirated 7.0-litre engine,” says Mercedes.
In the CL500 - the launch model this autumn - fuel economy improves by 22 per cent to 29.7mpg, with CO2 dropping by an equally impressive percentage to 224g/km.
The addition of turbos also spread the V8’s torque delivery across a wide rev range, Mercedes claiming that the “driver perceives no turbo lag” and that “an outstanding 442lb ft is available between 1600 and 4750rpm”.
The new V6 will feature in the S350 from the autumn and the CL350 from the winter. A significant change is a new block, which moves from a 90-degree vee angle to a more ideal 60-degree vee, which reduces vibration and allows Merc to drop the balancer shaft, cutting weight.
Still naturally aspirated, the 3499cc V6 nevertheless matches power and torque increases with better fuel economy and lower emissions.
Stop-start technology, which cuts consumption in traffic, is employed for the first time on a multi-cylinder Merc engine.
Peak output rises to 301bhp, up from 268hp, while torque rises to 272lb ft from 258lb ft. Merc says this torque peak is available from 3500rpm up to the 5250rpm red line.
But the major improvements are to fuel economy and CO2 output. In the bulky S350, the new V6 is claimed to be capable of 37.1mpg - a 24 per cent improvement - and 177g/km.
“These figures make the new V6 the benchmark in its segment for a comparable output,” says Mercedes.