Road Test: Jaguar XK 4.2 V8 2dr Auto

The only thing I don't like about the XK convertible is the slightly lame line Jaguar uses when pushed on why there are two new XKs - a coupe and a convertible - when the global benchmark car in this class, the Mercedes SL, combines the two with a folding steel roof. "Would you believe some people have bought both new XKs?" Actually, no, I wouldn't.

Unless you live in Stuttgart, where I assume there's been some kind of news blackout to stop locals discovering their icon has been toppled, you will know by now that in the new all-aluminium XK, Jag - yes Jaguar with its crap X-Type and forgotten F1 team - now makes the best GT in the world. Yes, better than the 6-Series, better than the Maserati, maybe pound-for-pound better than an Aston and even, if you really fancy a fight, a 911. My thinking here is that so comprehensively does the XK reclaim the GT label for cars with long, fast, easy legs, the 911 seems a bit frantic and unnecessary all of a sudden. On the right road with no dinner reservation I might be prepared to change my mind.

And that just leaves the Merc SL. Personally, as a coupe, I'd have the £65,000 Jag over an SL simply because the former manages to go like a sports car while still riding like a luxury car. The equivalent SL (on price), the 350, just doesn't cut it. It's not reasonable to bring the SL500 in here; it's got another 88bhp, but costs another £10k. Which makes it the target car for this summer's supercharged XKR, which gets another 120bhp - more than enough to blow the heavier SL into the weeds.

But there's more to the SL than a coupe, of course, hence Jaguar's defensiveness about its inability to fold a steel roof. I have no idea what the truth is regarding the Jag's  conventional cloth roof, but I buy the line that says folding roofs compromise the package and have the potential to destroy a car's looks. Just look at that hideous Lexus for some proof of that.

The SL is a striking-looking car, if a little tarty. The Jaguar, meanwhile, is quite beautiful and packs a decent-sized boot whether the hood is up or down. So maybe I'm saying this: if your sense of insecurity is overpowering, you could give up reading the Daily Mail - or failing that get the SL. But if you don't feel the world is out to get you, you should at least consider the XK convertible. It's a magnificent car.

It looks best with the hood down, of course, the absence of a big boot to stow a hard-top allowing Jag's designers to continue a single line right the way through the tops of the doors and into the flat rear deck. The hood stows under here, and the line deviates only over the XK's distinctive rear haunches, which somehow look more restrained without a roof to jazz with. The effect is less brutal than the coupe, and somehow more fun; it looks smaller, more of a toy, despite Jag's claim that the compact hood allows the rear seat space to give almost the same amount of room as the coupe. Sod all, then.

The hood itself is trick, a relatively simple affair of just three layers, an inner and an outer sandwiching a layer of ‘Thinsulate', a trick fabric you'll find in stuff like ski boots. The rear screen is glass and the whole thing stows under its aluminium tonneau in less than 18secs, even on the move, providing you're doing no more than 10mph.

It's a kink of car launches that you find yourself doing stuff a customer would never do, like climbing straight out of the coupe into the convertible (yeah, yeah, unless you've signed up for one of each). Should you do that, shift the ‘Jaguar Sequential Shift' six-speeder into D (come on, this is a convertible, you didn't opt for this model to spend your time flipping paddles), you'll notice a slight shudder as you hit your first road hole, but the chances are that after that you won't notice a thing. This is a very strong car, 50 - yes fifty - per cent stronger than the car that it replaces.

That's all down to the bonded and riveted (there's not a single weld in the convertible's frame) aluminium structure that tips the scales some 20-per-cent lighter than the last XK convertible. Jag says the monocoque body is so strong the convertible needs no extra bracing to compensate for the soft roof, a claim that's vindicated by the fact that by the time the car's reached the end of the assembly line, the convertible remains eight-per-cent lighter than its predecessor - the coupe only five-per-cent.

If that final kerb-weight reduction seems disappointing, think of all the safety, emissions and convenience features a 2006 car packs compared with a 1996 car. That's how long the old car was on the road.

The XK and the XJ, from which the new sports car has evolved the art of aluminium, are part of an elite band of all-aluminium cars. Now that the Audi A2 has expired, Jag leads the field in terms of production numbers. The A8 and various Ferraris don't come close. Jaguar needs applauding for that, not snubbing by government ministers opting for a Toyota Prius because, one assumes, they read about it in Heat.

The reduction in weight pays off against the clock, and the convertible now reaches 60mph in just six seconds - 0.3secs quicker than before. But although you can drive this car fast (where it feels faster than the possibly over-cosseting coupe) you probably won't. Life is too good on board to want to rush stuff. Just like the coupe, airflow management is exemplary. There's a diffuser but you don't need it.

And the cabin, bathed in sunshine, is a thing to behold: simple, modern, techy without being technological, it's how a 21st century British car interior should look. Hopefully, it's how the insides of all Jaguars will look soon.

Of course, what makes this car so special is not the ‘how' but the ‘what' and, like the coupe, the new XK convertible is a magnificent drive; its ride reassuringly direct without ever spoiling the treat a Jag should be; its steering just easy enough pointing straight ahead but utterly intuitive and predictable in the way it builds load in corners; its handling grippy but always sharp and always in communication; its drivetrain responsive and deceptively potent. It would be a very different story if the car was made of steel.

It is indeed a car you would want to drive every day of your life, but I suspect you wouldn't need to buy a coupe for when it rains. And I suspect that, now that it knows it has a winner on its hands, Jag will drop the line anyhow.

Michael Harvey