THINK of Jaguar's S-Type saloon and you tend to think of a businessman's executive chariot offering relaxed, silent transport.
But there is another, darker side to the S-Type and it comes in the form of the flagship R model which can be relaxed but can also be mind bogglingly quick.
For this wolf in sheep's clothing has a 400bhp supercharged V8 under its bonnet - and it knows how to use it.
From the outside there are just a few characteristics to distinguish this model from others in the range, the most obvious being the sporting mesh grille and the R badges on the side.
But it's on the road and when you put your right foot down hard that the distinguishing characteristics come to the fore and the car grows horns.
There is a whirr from the supercharger, a roar from the two exhausts and this big cat takes off like someone has trodden on its tail.
While every Jaguar made is quick there is no denying that the R versions are something special.
With the ability to reach 62 miles per hour in just over five seconds and a limited top speed of 150 miles per hour this is a car that easily qualifies in the supercar category.
Its acceleration is like that of a low flying jet and the loud pedal certainly deserves a great deal of respect.
That said this is a very civilised supercar which is quite happy in city traffic at crawling speed and as a result it's a very easy car to live with.
Earlier versions had five gears in the automatic box but two years ago an extra gear was added making the box much more refined and making it easier to get the best performance out of the car.
The gear changes are seamless and the Jaguar-developed, J-gate selector means that this is one automatic which is a delight to use manually for hands-on driving.
An electronic parking brake which comes on automatically when you take the key out and is released as you move off means one less thing for the owner to think about. You can use it manually by lifting a small chrome switch near the gear change but in practice it is rarely necessary.
Firm, yet delightfully comfortable, suspension - true to Jaguar's heritage - means superb cornering ability with no hint of roll and exceptional grip.
This is also a performance car which has a sensible boot, and if you do manage to fill it, the rear seats fold down to give additional space.
The R is not a cheap car by any standards. But if you have the money it is a car which I promise you will bring a smile to your face every time you drive it.
FAST FACTS
Jaguar S-Type R
Price: £48,600
Mechanical: 400 bhp, 4,196cc, V8 petrol engine driving rear wheels via 6-spd automatic gearbox
Max Speed: 155mph
0-62mph: 5.6 secs
Combined mpg: 22.5
Insurance Group: 19
CO2 emissions: 314g/km
BiK rating: 35%
Warranty: 3yrs/ unlimited mileage; 3yrs paint; 6yrs anti-rust