BMW 320D Convertible review (2004-2006)

It might seem odd that BMW is releasing a new version of its hugely popular 3 Series so close to its replacement, but when it’s a convertible, and a diesel then it’s perhaps understandable. It’s taken a while for the diesel engines to filter from the saloons into the coupe range, but they’ve proved popular. But a diesel engine in a convertible? Is this a niche model too far?

Not if you look at the engine’s credentials. With 150bhp on offer and, more importantly, 295Nm of torque at just 1,500rpm the 2.0-litre four-cylinder turbodiesel isn’t short of pulling power. With a combined consumption figure of 44.8mpg you’ll be an infrequent customer at your local filling station too. Importantly, given the majority will be bought by companies for their employees, the turbodiesel is Euro VI compliant, with its 167g/km CO2 emissions figure putting it in the 20% category for company car tax. That’s very significant, as a similarly priced 325Ci Cabriolet falls into the 32% company car tax band.

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While it makes sense for those buying with company money it’s unlikely that many private buyers will opt for the diesel. Why? Cabriolets simply don’t fall into the usual car buying parameters, you’re unlikely to consider them for sensible or practical reasons, by nature they are frivolous, emotional purchases bought as much for their image and style as anything else. Diesel engines are still the antithesis of this, usually being bought for their economy, ample pulling power and, in the UK at least, their company car tax credentials.

On the road

That’s not to say that the 320Cd Convertible isn’t an enjoyable car. It’s still a very stylish car to look at, despite being so familiar, and inside the interior retains the simple, ergonomically correct and well built feel of all 3 Series models. But it’s on the road that BMWs should excel, and the 3 Series has always been one of the best.

Here the diesel engine produces such an easy spread of power it delivers a relaxed drive. It’ll trickle through towns on low revs in fourth or fifth gear without complaint, accelerating effortlessly away without the need to change gear when you escape the confines of suburbia. Such is the torque that BMW really could have omitted several ratios from the sweet-shifting six-speed manual transmission, with first third and fifth ample for everyday driving, sixth gear proving an ideal motorway overdrive - comfortably cruising at up to 125mph on the autobahns around Munich.

Much to the amusement of the other drivers the brief high speed run was done roof down, in the rain. Wrap up well, hit the heated seat button, flip up the optional wind deflector and such open air antics aren’t uncomfortable, the rain only a problem if you stop. Do so and hit the button and the hood’s up in seconds. It’s obviously a touch more civilised roof up in October weather, and though there’s a good deal more wind and road noise apparent than its coupe relative, it’s a small price to pay for the ability to enjoy top-down driving, and one that cabriolet buyers are used to.

While a characteristic diesel thrum betrays the engine’s fuel choice at idle. However, unless you push it hard on the road it’s refined and unobtrusive. Drive it in the relaxed, but still pacey way in which it excels - riding along on its ample torque rather than hunting about the upper rev range - and refinement really isn’t an issue on the move. The steering is pleasingly direct too, and despite the removal of the structural strength of a conventional roof the cabriolet remained composed on all but the roughest bumps.

Seating is offered for four, admittedly at a squeeze if you’re an adult in the rear, and the boot is generous for a car of this type adding to its practicality. However, such things are usually secondary considerations when opting for a cabriolet. It’s for this reason that the 320Cd doesn’t really seem to fit. Sure, it drives convincingly and delivers decent economy and CO2 figures, but who but the handful of business drivers are ever going to notice?

At £28,350 for the SE model and £30,675 for the Sport it’s just too expensive against the £29,675 325Ci SE with its sonorous 2.5-litre straight-six petrol engine. Cabriolets are about bringing you closer to the elements, about experiencing more about the car. Given the choice the fantastic engine and exhaust note of the 325Ci is worth far, far more than the enhanced consumption and low CO2 emissions of the diesel.

Until diesel cabriolets can offer the emotional, and crucially, aural, appeal of a petrol engine they’ll remain business-friendly models with limited appeal. However, with the growing acceptance of diesel it’s a niche that BMW cannot afford to miss, and one that is becoming increasingly common. As such you can expect the new 3 Series cabriolet, due summer 2006 to feature a diesel engine far earlier than five years into its life. It’ll undoubtedly be good, as this one is, but the petrol versions will sound better, and for cabriolet buyers that’s what really matters.