The first time I saw pictures of BMW's Z4 it caused an almost physical revulsion, an instinct to recoil away from something astonishingly ugly. The gaping grille, the odd flanks and the pig-eyed headlamps just didn't seem to work. Even today when the 3.0si demonstrator car first arrived in the office, the lads were all over it like a rash whereas female attention was rather muted. It seems that when switching from Z3 to Z4 BMW also gave the little drop top gender realignment surgery. After a few days living with the car, though, a strange thing happened. I started to find myself sneaking the odd glance out of the office window at the car, intrigued by the clashing arcs, slashes and bulges. From certain angles it began to almost look good. I like most roadsters and if I could set the styling to one side for a moment, the Z4 would satisfy almost all of my other criteria but if you set out to build a car with controversial lines there are always going to be some who just plain don't like them. After much trying, I have to concede I'm one of them.

If the exterior design generates a little controversy, the same can't be said of the cabin styling. It's typically low-key but classy, BMW at their best. There's a broad centre console and clear dials. Space in the footwell is especially generous and it's possible to hunker down into a low driving position and feel really ensconced in rather than on the car. Always a good start. The hood is a superb fully automatic affair with no manual intervention required whatsoever. Simply prang a button on the dashboard and the whole thing retreats in less than ten seconds with no clips, latches, poppers or stress. The Z4 promises an easy life but who will these laid back takers be? It's an open secret that the Z4 - like its predecessor - has been targeted at the lucrative US market. Over here the entry-level 2.0-litre car will compete with cars like the Mazda MX-5 and Honda S2000, with the bigger-engined models instead looking to fry some bigger fish. These Z4s will have to convince serious drivers that they can cut the mustard.

Twist the key and the 265bhp engine snarls into life, filling the cabin with a malevolent grumble quite unlike what you'd be served in a 3-Series with the same powerplant. The reason is a piece of tubing that runs from the inlet manifold to the bulkhead. This contains a diaphragm that flexes like a drum as the engine breathes, channelling noise into the cabin. Whereas other manufacturers strive to quell cabin noise, BMW has taken the opposite route. It works too, but the sound effects are only part of the story. The Z4 3.0si also has to do the business when the blacktop is twisting into contorted shapes, throwing dips, bends, duplicitous cambers and blind brows at the driver. Whereas this scenario would tie a Z3 in knots, the Z4 is made, quite literally, of much stiffer stuff. In fact the chassis is torsionally stiffer than a Porsche Boxster's, which helps when transmitting that power to the tarmac. With a 155mph top end and a sprint to 60mph occupying just 5.9 seconds, the BMW is usefully brawnier - as well as a couple of thousand pounds cheaper - than its rival from Weissach. It can also more than hold its own as a driver's car. Although the steering feel can't match the Porsche, in almost every other area the BMW betrays the relentless march of technology. The stability control system does little to interrupt the enthusiastic driver, the gearbox can be slotted between the six ratios with a delightful firmness and the brakes are superb. Jab the 'Sport' button on the dashboard and the Z4 sharpens up its act still further, beefing up the steering and giving the fly-by-wire throttle a more aggressive software map to work with. It inspires enormous confidence and the little yellow triangle on the fascia strobes furiously through full commitment cornering, the only indicator that you are not, in fact, blessed with the car control of Juan Pablo Montoya.

Of all the roadsters currently for sale, the Z4 is one of the most sophisticated and accommodating. A whole host of electronic features make living with the car easy and all the engines have developed a reputation for exceptional reliability. This would seem to make the Z4 a sure-fire hit and if the styling appeals to you, go right ahead. Yes, Porsche's Boxster does have a credible rival.