Jaguar is about to replace its 12-year-old V8 engines with new 5.0-litre units that produce more power with lower fuel consumption and emissions.
They were announced at the Detroit Auto Show alongside the revised XK range and the new high-performance XFR, which will be the first recipients.
Two versions will be on offer a standard 382bhp engine and a 505bhp supercharged unit for the XKR and XFR.
Jaguar programmes director Mick Mohan says: 'We are a manufacturer of beautiful fast cars and these engines are all about putting the "fast" back into that.'
Chief engineer Malcolm Sandford claims they have class-leading responsiveness and low-speed pulling power and are quieter and cheaper to maintain. Service intervals have been stretched from 10,000 to 15,000 miles.
'This is a great engine as efficient as you can get in the automotive market and a benchmark for fuel efficiency,' he adds.
These all-new V8s have direct fuel injection, like diesel engines, and the standard version also has variable camshaft profiles and a variable inlet manifold to improve driveability right across the rev range. Only two small parts are carried over from the old 4.2-litre V8s.
The six-speed automatic gearbox in the XK and XF ranges has had to be beefed up to cope with the high torque levels of the new engines, and there are improvements to chassis, brakes and electronic safety systems.
'We have had to change the character of the cars, adding a more sporting element without losing refinement,' says Mohan.