BMW 120i convertible 01.08.2008

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Although it’s usually the high-output, technofreak wunderkind version that grabs the headlines whenever a new BMW product is launched, it’s as well to remember that the bulk of the company’s sales derive not from its X-this or M-that products, but from the relatively humble models.
This 120i convertible is a real back-to-basics car. You won’t find any acrobatic self-stacking steel roof, or a multi-cylinder marvel under the bonnet. It’s just a fabric-topped, front-engined, rear-drive convertible powered by a simple four-cylinder,
2.0-litre motor.

The question is whether keeping it simple like this reveals the clarity of the vision behind it or, in fact, exposes it as an uncomfortable compromise between truly practical coupé/cabrios such as the VW Eos and bespoke roadsters such as Mazda’s MX-5.
There is also the question of price: at £25,205 the 120i SE is positioned right at the top of the market, where its closest rivals are not only cheaper but also come with turbocharged engines. Can any car overcome that level of self-imposed disadvantage?

Design and engineering

It’s clear from the outset that while the 1-series has been on sale as a hatchback for over four years, this convertible is no afterthought. While an Audi A3 cabriolet looks remarkably like a guillotined A3 hatch, the 1-series convertible looks like a purpose-built sports car, and is all the better for it. Indeed, to our eyes at least it is by far the prettiest (or, we should say, least ugly) of all 1-series derivatives. You can choose a power output all the way from 143bhp to 306bhp in the range, although BMW’s initial expectations were for this 168bhp 2.0-litre version to make up the bulk of sales. As orders have started to flow, however, the company has been surprised by the strong demand for the diesel 120d version. But then the 120d is more powerful, quicker and more frugal than the 120i and has lower CO2 emissions and potentially better residuals, all for a premium of just £805.
Still, seen in isolation at least, there seems little to criticise about a 2.0-litre engine producing 168bhp at 6700rpm, while the 120i’s torque peak of 155lb ft at a reasonable 4250rpm is similarly at the upper end of reasonable expectation. Even so, that’s not a huge amount of clout to propel a car weighing over 1.5 tonnes – a steep premium of 140kg over a three-door 120i hatchback and only a few kilos less than the weight of a tin-topped Volkswagen Eos.
Looking after affairs in the corners, as in other 1-series derivatives, is BMW’s well proven system of MacPherson strut-type front suspension and a five-link axle at the rear.

Interior

One or two minor glitches aside, the cockpit area of the 120i convertible represents BMW at its clear-thinking best. There’s no infernal iDrive controller (unless you spec the optional satellite navigation system, in which case you get an entirely different dash) and no splat of buttons to identify and understand.
Simplicity is all in the layout of the controls, while the driving position allows the wheel to be pulled close to the chest of even very tall drivers. The dials are the least complex – and therefore the most legible – fitted to any BMW, and apart from pedals fractionally offset to the right, the relationship between the driver and his or her primary controls is exactly
as you’d wish.
It’s let down only in the details: the seat is set a fraction too high, betraying its hatchback roots; there remain some inappropriately cheap plastics, particularly the hard and scratchy instrument cowl, and the graphics
of the allegedly ‘Professional’ radio look cheap and nasty.
If you stray beyond the immediate environs of the driver’s seat, more significant problems arise. The rear seats are suited to small children only and even they will find the seat backs uncomfortably upright and legroom behind an average-sized adult seriously restricted. There’s also precious little space to store anything, with a small number of tiny, all but useless trays and bins and a pathetic glovebox. There aren’t even any map pockets behind the seats.
The roof, however, works very effectively; BMW says it takes 22sec to raise or lower, and we timed it at 24sec up/23sec down on a cold day. Best of all, and unlike its rivals, it can be operated at any speed below 31mph, so there’s no longer any need to find a parking space or crawl along at walking pace to operate it. If you’re caught out in a sudden downpour, that’s a real advantage.
BMW claims the roof is so well designed that it offers levels of refinement comparable to the metal-top 3-series convertible, but not in our experience. Although air flow is managed very well with the roof down (and even better with the optional deflector in place), with the hood up there is notable wind noise at motorway speeds, subjectively far beyond what you’d expect from the equivalent closed car.

Performance

While the performance of the 120i is baldly impressive for a car of its specification, it’s not half as impressive as the performance of other cars with the rather higher specification that the same or less money can buy.
The British-built 2.0-litre motor is adequately smooth and commendably linear in its power delivery, given its high specific output, and will rev past 7000rpm with enthusiasm rather than complaint. Like every other 1-series convertible, it comes as standard with a six-speed manual gearbox with expertly chosen ratios – quite short and close to match the characteristics of the engine – and a delightful action allied to a light but precise clutch. Hook all these elements together and it doesn’t exactly rip off the line, but a 0-60mph time of 9.0sec is just within the bounds of respectability and its 137mph top speed somewhat more so.
But this motor is nevertheless one that requires work to give its best. If you’re lazy with it and leave it in top gear, routine tasks like accelerating from 50-70mph take an age (13.2sec, to be precise), while the superior torque of, say, the turbo motor fitted to the Eos allows it to dispatch the same measure fully four seconds quicker. Even so, this is less of a problem than might at first be supposed, not least because changing gear to keep the engine on song is no chore and rather suits the car’s character.
Nor is there any problem with the brakes. The pedal feels perhaps a shade too light, but progression, feel and retardation are all beyond serious criticism, the 120i stopping from 70mph in a respectable 46.5m.

Ride and handling

You would expect any BMW to tackle this category with confidence, and even one as modestly powered and structurally compromised as the 120i convertible acquits itself well on the road. As previously mentioned, the measures taken to counteract the inherent weakness of the convertible layout have added considerably to the weight of the 1-series, but it’s an impedance felt more in a straight line than through the bends, for the 120i maintains a near 50/50 distribution and is, for the most part, an extremely tidy handler.
BMW has not made the mistake of fitting ultra-quick steering in an attempt to inject a feeling of artificial agility into the chassis, and despite the usually feel-sapping qualities of electric assistance, the 120i is a delightful car to guide at medium effort down a typical British back road. It won’t create a virtual connection between your backside and the road
as will a Lotus Elise or even an MX-5, but it still makes you feel very much part of the action, rather than a bystander like in an Eos or an A3 cabriolet.
The suspension is surprisingly soft, but this actually helps in most cases, providing good traction out of slow corners and suppleness over undulations. Only if you drive with a conviction that, frankly, is unlikely to visit many typical 120i drivers can you feel the chassis start to porpoise and corkscrew a little as its damping struggles to contain the body’s desire to pitch and roll.
The rest of the time it rides remarkably well. Scuttle shake is absent on all but the worst surfaces, and small imperfections are absorbed as if they weren’t there. If, when they were first introduced and promptly wrecked the ride of the 5-series, you had told us that run-flat tyres could be made to work this well, we probably would not have believed you.

Buying and owning

There’s no question that the 120i SE convertible is an expensive purchase, albeit one that’s likely to hang on to its value longer than most rivals.
Once it’s yours, however, it should prove exceptionally cheap to run for the class. Not only is the engine outstandingly frugal, thanks to both its inherent design and BMW’s Efficient Dynamics package, but it also is a low CO2 emitter, which means cheap company car tax and Band D Vehicle Excise Duty. During its time with us it returned a best of 34.6mpg, although during performance testing it slipped back to 11.7mpg. Overall the figure was 31.2mpg, which is about the worst any owner could expect, providing a real-world range of at least 360 miles.
In SE trim, the 120i is reasonably well equipped with all the active and safety gear you’d expect and a fully electric roof.

History
Six years ago BMW showed a concept called the CS1, a roadster looking remarkably like the one on these pages. It sparked the entire new BMW ‘flame surfacing’ look. Back then it was powered by a puny 115bhp 1.8-litre engine which would never suffice today, but its dimensions and looks have survived the transition to the present day intact. Sadly, that’s more than can be said for the aluminium and neoprene that clothed the interior of the CS1.

Well Balanced

On the low-grip circles inside T7 the 120i is as well balanced as its near 50/50 weight distribution would suggest.
Here the modestly specified spring rates have the 120i running out of ideas reasonably quickly. If you leave the two-stage standard stability control activated, the car can be easily contained, thanks to the balance inherent in its weight distribution and the concentration of its major masses — the engine and gearbox — within the wheelbase. Turn all the tricks off (and BMW is to be commended simply for making this permissible) and the 120i can lurch quite suddenly into understeer on the way into a corner or, should there be an unplanned event like a change of surface or line, slightly messy oversteer at the exit. It’s not the kind you can exploit — it has neither the power nor the limited-slip differential for the type of tail-out histrionics beloved of M-series cars — but nor is it unduly alarming. A quick correction and it’s soon all pointing straight again.
In the more isolated circumstances of a wet test track the 120i exhibits extremely mild manners, gripping admirably and needing very little correction to post a respectable and repeatable lap time.

Under the skin

One of the smartest innovations on the 1-series convertible is something called SunReflective leather. This was first offered as part of BMW’s ‘Individual’ options tailoring programme on the 6-series in 2005, and it’s now standard on every leather-upholstered 1-series cabrio.
Through the use of special pigments, this system works to reduce the surface temperature of the leather when left in direct sunlight — stopping you from getting the backs of your legs burnt on a blazing hot day when you’ve left the car parked with the top down. BMW claims it can reduce the temperature of dark shades of leather by as much as 20 degrees.
In another piece of impressive joined-up thinking, the automatic air conditioning system has a convertible mode, whose strength and temperature is governed not by the cabin temperature of the car, but by the exterior temperature and ‘sunlight factors’.