Sunday 16 February 2014

BMW downsizes from four to three

BMW has conceded finally to the wisdom of the pack. It has adopted front wheel drive for its new 2 Series Active Tourer.

It has also nodded in the direction of downsizing with its use of three-cylinder engines in the model line-up, a feature created by Sir Alec Issigonis..

Following on from the coupé as the second member of the new 2 Series range, the Active Tourer, according to BMW “combines dynamism, style, elegance and practicality in one cleverly packaged car”. The new range will replace the 1 Series.

The new 2 Series Active Tourer also has all-new transverse engines, a feature created by British designer Sir Alec Issigonis in the early 1950s.

One of Issigonis’s most famous quotes declared “When you are designing a new car, never, never, copy the opposition”. He worked on the ADO15 project which, with draughtsman Jack Daniels they evolved into the British Motor Corporation’s Mini, launched in 1959.

The three-cylinder engine powering the 218i Active Tourer has an “ultra-low-friction, all-aluminium core” which is part of a newly developed modular family comprising light weight, high-performance and fuel-efficiency, equipped with BMW’s  “TwinPower Turbo technology”.

The result is a CO2 emissions of 115g/km for a peak power of 136hp. An Audi four-cylinder 1.4 TFSI, for example by comparison, of 140PS offers a CO2 emissions level of 109 g/km.

BMW claims that with turbocharging, direct petrol injection, double-Vanos variable camshaft timing and the “longer firing intervals of the three-cylinders”, it is possible to precisely match the engine cycle to varying power requirements.

As a result, throttle response is sharp, and the engine develops large amounts of torque from only slightly above idling. Peak torque of 220Nm is reached at only 1,250rpm, and sustained to 4,300rev/min.

BMW notes: “further advantages of this lightweight, compact three-cylinder engine are its vibration characteristics”.

In fact, the disadvantage of a three cylinder engine is its unbalance which, to ameliorate, requires a balancer shaft – adding weight, complication and cost.

BMW adds however, “the small amounts of engine roll torque are completely eliminated by a balancer shaft, while the combination of a dual-mass flywheel and a centrifugal pendulum absorber, unusual in this power class, eliminate irregular running, ensuring refinement even at the low end of the engine speed range.”

Completing the two engine line-up at launch is a new four-cylinder diesel engine fitted to BMW 218d Active Tourer.

Turbocharged and common rail direct-injected, “optimised performance with optimised efficiency see CO2 emissions as low as 109g/km, power of 150hp and a peak torque of 330Nm”.

BMW points out that the “new” diesel engine has a “friction-reduced” core engine, improved thermodynamics and injection pressures of up to 2,000 bar. This engine too has a dual-mass flywheel with centrifugal pendulum absorber.

The standard transmission is a newly developed six-speed manual unit. Optionally, in conjunction with the three-cylinder engine, a six-speed automatic transmission can be specified.

For the four-cylinder engine, a new eight-speed automatic transmission has been developed, which is specially adapted to take account of the front-wheel-drive configuration and the transverse engine.

All transmissions feature auto start-stop, while the automatic versions further improve vehicle efficiency with a coasting function.

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