So let's meet Chrysler's Crossfire, so-called for the way the flank-ridges cross over on the doors' upper surfaces. It signposts the American company's new design language, with bonnet ridges to echo both the pre-war Chrysler Airstream and the also pre-war Chrysler Building in New York, plus a semicircle grille and a crisp outline.

An American two-seat coupe to take on Europe's best. It's a nice idea, as is the chance to drive it in the very American environs of San Diego. But how American is it, exactly?

I ask the question. 'Well, a few of the medallions and part of the stereo system,' replies a Chrysler representative. For the hidden truth, the double-edged sword of quality cred and identity discred, is that this is pretty much a German car. It's based on modified Mercedes SLK (the current, not next, model) underpinnings, and it's built by Karmann. Oh, and it was styled - some might say over-styled - by a man from Birmingham. West Midlands, not Alabama.

The man from Brum, Andrew Dyson, knows how to extend a brand. He did the VW Touareg in a former life, bringing credible uprange 4x4dom to Wolfsburg, and now he's revived the idea of 1950s US auto-jewellery to a long-bonneted, boat-tailed, fast-backed sports coupe. The devil, and the salvation too, is definitely in the detail here. Those bonnet creases are continuations of the vertical grille slats. Both headlights and tail-lights have 'cooling fins' around them. The air-exit behind the front wheel has three silver strakes. The side-cross mentioned earlier begins as an indentation and grows to become the top of the rear wing.

And then there's The Ridge. It runs from the centre of the front valance right over to the tail, finally to bisect the two trapezoidal centre exhausts. A similar ridge runs along the middle of the cabin, from the tunnel, up the console and over the facia-top, so that's how the driver sees the bonnet-ridge resolve itself. It's all very concept car, as the Audi TT was/is. Here, though, the concept changed more on the route to production, losing the vertical headlights ('Too Cadillac,' says Dyson) and being reconfigured onto the SLK platform. The show car tantalisingly used various pieces of Prowler and Viper under the skin.

Amazingly, the whole process from concept to production took just two years, helped by the availability of that Mercedes hardware (39 per cent, by value, of the Crossfire's make-up). Does that mean the new Chrysler will feel like an old Merc? If so, then, rival coupes won't have to worry too much.

Time to find out. I'm installed in the low-set, but height-adjustable, driving seat. Instantly I see SLK signifiers: the steering wheel adjusts for reach but not rake, the column stalk is overburdened with both lighting and screen-cleaning functions. The decor is not at all Merc-like, though: it's squarer-cut and a lot more silvery. There's a satin-aluminium look for the door pulls and some other details, but not for the centre stack which instead is sprayed in silver paint, switches, knobs and all. 'It hasn't turned out quite as I intended,' says Dyson. 'We may make a change.'

The other slight surprise-and-disappoint feature is the array of crosshead screws on view as soon as you open the glovebox. Otherwise, though, this is a quality cabin with soft-touch textures, good fits and solid assembly. A bit Merc-like, actually.

So, unfortunately, is the six-speed manual gearshift and the driveline with which it interfaces. The engine - Mercedes-Benz's usual 3.2-litre, 215bhp V6 with one inlet and two exhaust valves per cylinder - fires up with an encouraging rip; attitude-wise, the Chrysler is already out-hipping the Benz. Then you prod the lever into first gear (the clutch pedal is already down because it had to be to start the engine, this being an American car), and your heart sinks at the loose, springy flop felt under your palm. Clutch up, and away. Into second - clonk goes the lever - and a choice driveline kangaroo as the clutch re-engages. This is going to take some practice. (Strange how, the next day, the latest-model Viper I drive has a transmission of precise engagement and perfect manners despite the vast torque it handles.)

The next gears up the scale slot into the acceleration curve more tidily, but even by day's end I will have executed just one perfect first-to-second shift. And the harder you try, the harder it gets. Luckily, the Crossfire has other attributes to make up for the transmission's intransigence. The engine, for example.

This V6 is not Mercedes-Benz's finest achievement, I always think when I drive it in Mercedes surroundings. Not that sweet, not that crisp under-pedal; usually I end up favouring a 320 turbodiesel version. In the Crossfire, though, it finds its true voice and plenty of it. The engine isn't loud, but it sings a free-breathing tune with defined edges and a healthy blare. It's also very smooth and very torquey; in short it's a V6 that does all the right things.

So far, so good. But how will old-SLK technology cope with corners in a competitive world? Do not forget that the SLK is the last Mercedes car with a recirculating-ball steering box, once commonplace, lately the preserve of big saloons, seriously anachronistic for a millennial sports car. It doesn't matter. The SLK is a stodgy steerer, but the Crossfire - helped by a much more rigid body with a roof - is not. It's a bit variable-ratio-ish, starting slowly then speeding its response, but the feel and weighting are fine, lost motion is absent, fluidity of bend-attack is assured.

And, being rear-wheel drive with hefty 19in rear tyres (18in up front), and being firmly damped but without quite the movement-constriction of a TT so it can breathe better over bumps, it does bends rather well. There's loads of grip, the front wheels hold on tight even when the bend turns tighter, and there's enough torque to tighten the cornering line in a final squirt ready for the next straight. It's good clean-responding fun, not as hard-edged as Nissan's new 350Z, not as hard on the senses either. For a response/comfort comparator, think Porsche Boxster.

There's also, I have to tell you, a five-speed automatic version with AutoStick manual control. Yes, it's a Mercedes system with that AMG trick of pre-selecting the optimum overtaking gear if you hold the lever in downshift for a couple of seconds. It works well, it shifts smoothly, it makes for a much more pleasing Crossfire. Which, for us, is not the way it should be at all.

Chrysler knows the manual needs fixing. If it happens, preferably by the autumn UK on-sale date, the Crossfire will be a temptation: Audi TT 225 money, much more dynamic soul and never mind the confused parentage. If not... then what a shame.