Out of the two German sporty convertible, the 125i comes out on top – soft top, that is

Price: £26,020 (range spans £22,335-£32,415). On sale April
Engine: 2,996cc, six cylinders, 24 valves, 218bhp at 6,100rpm, 199lb ft at 2,500-4,250rpm
Transmission: six-speed gearbox, rear-wheel drive
Performance: 148mph, 0-62 in 6.8sec, 34.9mpg official average, CO2 195g/km

A few weeks ago Audi launched its new A3 cabriolet, a neat car notable for a soft-top roof able to deploy in just nine seconds. The Audi briefly had no rival. Now it has. It's a BMW, in the shape of the 1-series convertible. This, again a soft-top rather than the coupé-cabriolet design favoured for the bigger open-top 3-series, is both the newest 1-series and, in a way, the oldest.

Back in 2002, BMW showed the CS1 concept car. It showed how a future small BMW – the 1-series – would look, and it was a convertible. Today's car is an exaggerated version of the original, with more pronounced wheel arches, more sculpting of the sills and more wraparound for the rear lights, but the stance, the upright nose and the curved sill line remain.

Not everyone likes the style. The blobby coupé looks worst, the three-door hatch the least troubled, but to me all have curious conflicts of lines. However, because it's the simplest the convertible is also the most pleasing to the eye, which is drawn to the rather handsome waistline ridge without distraction from clutter above. Part of the clean look is down to the way the hood is stowed under a flush-fitting cover. Aesthetics drove this design decision, because it is neither as practical nor as cheap to make as the Audi arrangement. But who buys a convertible for practical reasons? It's a moot point.

That Audi nine-second hood-fold is quite a feat. It's achieved partly by dispensing with the separate hood cover and its time-consuming movements, all of which makes the Audi's boot surprisingly capacious. By contrast the BMW's boot suffers an incursion from the well in which the bulkier hood assembly sits when folded, but at least the boot is still bigger than that of a typical coupé-cabriolet.

The complete 1-series hood movement takes 22 seconds, but, almost unbelievably, you can raise or lower the hood even when driving at up to 30mph. I tried it and it works. You might prefer the BMW's uncluttered roof-down profile, with no visible rear roll-over bars because they pop up only when sensors detect the need – when you're about to turn your BMW upside down, for example. Those of the Audi, by contrast, are always visible, making for a cluttered image.

Maybe the way the BMW feels to drive will sway you one way or the other. You can tell from the way the front wheels are pushed far forwards that you might be in for an alert, dynamic drive. Styling and the driving experience don't necessarily tally in such a simple way, of course, but the BMW looks like that because it has rear-wheel drive and the position of the front wheels isn't dictated by where the driveshafts need to be.

Rear-wheel drive stands a chance of making the 1-series feel more like a proper sports car, too. And then there are the engines. There are no six-cylinder A3 cabriolets, but BMW offers us the 125i and 135i which, confusingly, both have 3.0-litre, straight-six engines. A straight six is a rare treat nowadays, yet it's the smoothest-spinning of any engine configuration on offer. One comes with two turbo chargers and 335bhp, the other with normal aspiration and 218bhp, which is plenty.

It's that latter, the 125i, that I try first. Like all current 1-series cars, it has an interior trimmed in higher-quality materials than the first Ones. So it feels like a proper BMW inside, as well it should given its £26,020 price in SE trim. You sit low and snug, but with much more room to move than any rear passengers. They get more legroom and headroom than I expected.

Leave the rear passengers at home and you can fit the wind deflector instead. Like most such devices fitted to many open cars, it works well in stopping the flailing and tangling of tresses if, unlike mine, your head is so blessed.

An open car lets you hear more of the engine's voice, which is a good thing if the voice is sonorous. The 125i's creamy engine is certainly that, and it's powerful enough to make a genuinely rapid car: 6.8 seconds to 62mph, 148mph should the moment arise. It has a delightfully smooth and easy gear change, powerful and progressive brakes and enough adjustments for a near-perfect driving position.

Sharing equal billing with the delightful engine is the way the 125i zips through corners. I didn't like the electric power steering on early Ones, but it's much better now with a feeling of precision lacking before. Combine this with the front wheels' determined grip and the way you can tighten your line out of a bend with a press of the accelerator and you have the recipe for a great time. More fun than the Audi? Frankly, yes.

I also tried a four-cylinder 120i; the initial-reversal is crucial, because it denotes less kit such as a blank space where the iDrive controller should be. No great loss, but the engine is down to 170bhp. Performance feels more reduced than you would expect although it's still fine. It sounds ordinary instead of special, and it still costs £24,065. That makes the 125i seem much better value.

But even the potent, twin-turbo 135i just manages to scrape under the 225g/km mark that signals massive road tax for Londoners. That's a relief, then. Personally, though, I'd be very happy with a 125i. I haven't enjoyed a convertible so much for ages.


Alfa Spider 2.2 JTS: £25,995
Meant to be a sports car but really a two-seat convertible based on a shortened 159. Engine is pedestrian; front-wheel drive and floppy structure spoil the drive.

Audi A3 2.0 TFSI Sport cabriolet: £25,500
Firmer, keener suspension doesn't spoil the ride and 200bhp, four-cylinder turbo engine is lively and hood is super-fast. Fun to drive but BMW is more so.

Volkswagen Eos 3.2 V6 Sport: £28,427
Part-Golf, part-Passat under the skin, and one of the better-looking coupé-cabriolets. Good to drive with narrow-angle, 250bhp V6 and DSG semi-auto gearbox.

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