Jaguar XF SV8

Price: 54,900 (range starts 33,900), on sale February

Engine: 4,196cc, V8 cylinders, 32 valves, supercharger, 416bhp at 6,250rpm, 413lb ft at 3,500rpm

Transmission: six-speed auto, rear-wheel drive

Performance: 155mph, 0-62 in 5.4 seconds, 22.4mpg official average

CO2: 299g/km

I think he had a gun. Certainly, he was mighty mad. The Stetson-wearing man outside the caf in Tortilla Flat, Arizona, was mad because he had just been overtaken by a red Jaguar. He was trying to identify which Jaguar had been engaging in such an un-American activity, and was photographing a red XK coup.

Thus does the new Jaguar XF pass the identity test. A non-expert, pickup-driving member of the public confuses it with an XK, which means Jaguar need not fear for the new saloon's visual credibility. For the speedy car was a red XF, and inside it was me.

Why, you may ask, was I driving the new, and very British, XF in Arizona? I'd have preferred to drive it on UK roads, but Jaguar needed to ship some pre-production XFs to its US dealers as mechanics' training cars, so we had a preview prior to the main launch next month. So we can give Jaguar the benefit of the doubt over one car's rear-wheel vibrations and a touch-sensitive glovebox catch with a bad case of amnesia.

A glovebox catch. Why is that worth mentioning? Because, when working, it is one of many features of the XF that surprise and delight. Set into the trim just above the glovebox is what looks like an RAF roundel. Touch it, and the lid should open. The interior lights have similar touch-sensitivity, and when it works it's wonderful.

Another nicety is the way the XF comes to life when you sit inside. The starter button pulsates gently until you press it, upon which a round selector knob rises out of the centre console. This is the rotary selector for the automatic transmission fitted to all XFs, whose functions are supplemented by paddle-shifters on the steering wheel should you wish to render your auto into a manual.

At the same time as the selector breaches the surface of the console, four fascia air vents appear where there had previously been plain aluminium. If this first XF encounter is at night, you will also notice how the console's other switchgear is outlined in light, like the keypad of some mobile phones.

Night or day, the interior of this replacement for the S-type, and the car on which Jaguar's future depends, is a delightful place. Like the exterior, it is meant to evoke a Jaguar atmosphere without sinking into the mire of retro design. So it has wood, but used in unusual ways. Think of it as "reversed out": the wood might be where you would expect leather or aluminium, and vice versa.

All XFs have leather upholstery, by the way, including on the dashboard top and door trims. There's no low-spec, cloth-trim model because Jaguar, as managing director Mike O'Driscoll puts it, is in the entertainment business rather than the transport business. Yes, there will be a turbodiesel version that uses the Peugeot/ Jaguar/Land Rover 2.7-litre V6, but on past form this unfeasibly smooth engine will lack little in entertainment value. Other engines are a 3.0-litre V6 petrol unit and a pair of 4.2-litre V8s. It is these that Jaguar previewed in Arizona, one of 298bhp, and one with a supercharger and 416bhp, both as used in the XK range.

Under the skin, the XF is based on the S-type, but even though the structure is stronger, the new car weighs just 15kg more. Partly this is through the use of aluminium, employed for the bonnet and much of the suspension. The XF is roomier than its predecessor, but tall people may still feel cramped in the back. As consolation, the rear seats' backrests fold forward to create a cargo space.

And so we come to the vital aspect of the XF. Not the driving qualities important though they are but the way it looks. To be a Jaguar stylist is to have one of the hardest jobs in the motor industry. How do you make modern a visual image so firmly rooted in the past, while keeping your designs recognisably Jaguar? The XK showed some of design director Ian Callum's new thinking, and the XF continues the themes of metal stretched to the edges of the wheels, of references to the old headlights and bonnet interpreted in a new way, of stark curves and minimal adornment.

So what makes it a Jaguar? The frameless front grille hints at the first Jaguar XJ6 of 1968, a reference made stronger by the bonnet bulge and headlamp fairings. The rear quarter windows' shape is trad-Jag, and the front and rear quarters are quite XK-like. For me it works, and it's hard to imagine how else a new Jaguar saloon could credibly look.

And to drive? I tried the regular V8 first, loved its quietness, its suppleness, the fluid way it took corners. The steering isn't ultra-sharp, but its responses are properly proportional and turning the wheel requires just the right amount of effort. It's a car that draws you in to the driving process rather than trying to distance you from it, helped by the best automatic transmission on offer today. Its manual mode works quickly and definitely enough to feel like a proper, well-judged mechanical shift, even automatically bringing the engine speed up for a smooth downchange.

This hefty saloon feels lithe and agile when exercised, the mood helped by the metal-edged woofle from the exhaust, and you can't help thinking it a more interactive, more satisfying companion than its obsessively functional German rivals. You warm towards it very quickly, helped (optionally) by a fine, British-made stereo system from Bowers & Wilkins.

Then you try the SV8. This doesn't assume the harder-edged role of the old S-type R the future XFR will have a new 5.0-litre engine and around 500bhp but is still a very sporting machine with its very low-profile tyres and its little button bearing a chequered flag. Press this and the transmission becomes more responsive even than in its sport mode.

Now you can really enjoy the engine's vast and easy pulling power, delivered with the subdued whine of a supercharger while the suspension still smothers bumps in proper Jaguar fashion. It's fabulous fun on a good, twisting road, shifting gears manually and seeing the giant gear-numbers flash from white to orange as the engine's rev-limit approaches.

The Jaguar XF needed to be good, and it is. Jaguars have never been short of charisma, but matching their rivals objectively has not been so easy. The XF achieves both, admirably, and now the company seems poised for a success that has eluded it for too long. Why Ford seeks to offload it is more of a mystery than ever.

The rivals

Audi S6 55,475

A 5.2-litre, 435bhp, Lamborghini-based V10 powers this fastest A6, and 4WD helps get the power to the road. Not the satisfying drive you'd expect, though.

BMW 550i M Sport 48,305

Quickest 5-series below the M5 has a 367bhp V8 and can give a rousing drive. Good value next to Jaguar, but slightly slower and trails on aesthetic appeal.

Mercedes-Benz E500 Sport 49,187

Hefty 5.5-litre V8 sends 388bhp through a seven-speed auto and fractionally outpaces Jaguar. A great car, but less lithe than Jaguar and showing signs of age.