Essence refined: this BMW feels just as a BMW should

Engine: 3.0-litre turbocharged in-line six cylinder petrol

Transmission: eight-speed automatic/six-speed manual

Power: 320PS at 5,800rpm

Torque: 450Nm at 1,300 to 4,500rpm

Fuel consumption (combined cycle): 37.7mpg, 35.3mpg (auto, manual)

CO2 emissions: 175g/km, 188g/km (auto, manual)

Top speed: 155mph (artificially limited)

Acceleration (0-62 mph): 4.9/5.1 seconds (auto/manual)

Price: £29,995 (for three-door – the five-door model costs £30,525)

Driving the new M135i is a rare pleasure. That’s not so much because it’s a hard-core sports machine (although it is very quick indeed) but because it provides a vivid reminder of the sort of car that made BMW great.

Once, it was easy to describe the essence of a true BMW – a coupé or saloon body, a rear-wheel drive powertrain, a near 50:50 front/rear weight distribution in the interests of handling balance, and, most important of all, a smooth, free-revving in-line six-cylinder petrol engine. Six-cylinder engines extended well down the range to the 320 and 520 so if you could afford the entry-level 3 or 5, you only had to find a little bit more cash to get a “proper” BMW.

But BMW has never let its history stand in the way of improving the practicality, performance, efficiency or environmental impact of its cars and has, where necessary, moved away from its traditional recipe to embrace SUVs, estates and diesels. Soon there will be electric BMWs and it is even being said that the dreaded front-wheel drive may turn up in a car wearing the famous blue and white badge before too long. Today, the typical BMW driver sits behind a four-cylinder diesel engine in a car that was probably chosen for him by his employer because it’s the most tax-efficient choice; he probably doesn’t know or care whether the diesel engine drives the front or rear wheels. It’s hard to argue with what BMW is doing. Its EfficientDynamics programme has brought huge improvements in fuel consumption to cars that are still very quick and enjoyable to drive, while the company’s sales go from strength to strength – and yet something has been lost.

Well not entirely, because at the extremes of the BMW range there are still some cars that follow that classical BMW recipe, and, in particular, still have in-line six-cylinder petrol engines under their bonnets. The M135i is such a car. The first thing to say is that it is not the 1-Series’ counterpart to models such as the M3 or M5; it is instead an “M Performance” model, a new type of vehicle in the BMW hierarchy designed to be sportier than the M Sport line without being a full-blooded “M” car. That leaves the way open to an even sportier M1, of course, although it’s unlikely to be called that out of respect for the car of that name, which took BMW into the world of mid-engined super-cars in the late 1970s.

On the road, the M135i feels just as a BMW should, or used to in the old days. The straight-six engine still has the gloriously refined snarl of its predecessors, even if it is a little muted thanks to turbocharging - and that turbocharging is a worthwhile addition, because it eliminates the main weakness of the lovely old BMW petrol sixes, modest low-end torque. That BMW balance is there in abundance too, complementing the rear-wheel drive layout, a big plus, not so much for tail-out reasons but because it makes the car feel sweeter even in normal driving.

As an alternative to the standard six-speed manual, you can buy the M135i with an optional eight-speed automatic gearbox. The eight-speeder is a conventional automatic supplied by ZF, rather than a dual-clutch DSG-style ‘box of the sort you’d expect to find in a high-performance car but it actually delivers better acceleration, economy and emissions than the manual, shifting rapidly and smoothly to keep the M135i’s engine “in the zone” where fuel consumption and performance are concerned.

The arrival of the M135i also coincides with the introduction of the new three-door Sports Hatch body-shell for the 1-Series. As a three-door, the new car costs £29,995; adding a second pair of doors takes the price to £30,525. It’s worth it.

On sale in the UK: 22 September 2012

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