JAGUAR calls it the whisper effect. Switch on the engine, walk round the car and listen for the sound of silence.
That's the sort of confidence the prestige manufacturer has in its latest 2.2-litre diesel engine, one that since September has put a performance oil-burner under the bonnet of the Liverpool-built X-Type.
Jaguar may have been late onto the diesel scene compared to its principal German rivals, but since embracing the technology just over two years ago, giant strides have been made.
This 152bhp powerpack is the same four cylinder unit doing service in the potent Ford Mondeo TDCi ST, but with a string of new refinements.
For instance it already meets the stringent Euro Stage IV emissions regulations, but more importantly it is a quieter, more polished engine.
And boasting a Benefit in Kind rating of 18 per cent it also has one of the lowest company car tax bills of any in its sector.
Take to the roads and the level of power you would expect from a performance diesel is there along with an overtaking 'overboost' set-up which provides a hefty 400nm of pulling power for more instant response.
Official figures are 0-62mph in 8.9 seconds with 137mph top speed, and the introduction of a new six-notch manual transmission means high speed driving can be enjoyed at extremely low engine speeds - a little under 2,000rpm at 70mph.
The Ford-owned company has also identified female drivers as being attracted to the marque - and particularly the X-Type estate - so the clutch operation has been deliberately eased to appeal to women.
Overall the feel transmitted from the steering, and the way the X-Type handles, is one of confidence - all achieved with, in my case, an average fuel economy of a reasonable 43 miles per gallon.
The 2006 range sees two fresh body colours, Winter Gold and Indigo, introduced along with 15-spoke Antares alloy wheels and a Bluetooth wireless phone system.
It comes in four trim levels - Sport, SE, Sovereign and Sport Premium - with prices from £22,995 for the Sport saloon and £24,165 for the estate.
Standard features on the Sport model are extensive and include uprated suspension, Piano black veneer, colour-keyed exterior, rear spoiler, dynamic stability and cruise control, CD autochanger, heated front seats and that rare bird in the modern car, a cassette player.
You have to pay extra though for the likes of electrically adjustable seats, voice activation, sat-nav, Bluetooth technology and Xenon headlights.
As to comfort, no shortage of upmarket touches punctuate the cleverly designed interior, while the seats are nicely bolstered, if on the firm side.
In fact the only area for serious criticism is the back, where a centre passenger draws the short straw - perched awkwardly with legs astride the transmission tunnel while those either side relax in nicely moulded seats.
And the whisper effect - well perhaps that's pushing credibility a bit too far.
FAST FACTS
Jaguar X-Type 2.2D Sport
Price: £22,995
Mechanical: 152bhp, 2,198cc, 4cyl diesel engine driving front wheels via 6spd manual gearbox
Max speed: 137mph
0-62mph: 8.9 secs
Combined mpg: 47.1
Insurance group: 15
CO2 emissions: 159g/km
BiK rating: 18%
Warranty: 3yrs/unlimited mileage; 3yrs paint; 6yrs anti-rust