Saturday, 29 January 2011

News Roundup 28 January 2011

BMW to replace six-cylinder engines with turbocharged fours?

For me BMW is synonymous with six-cylinder engines and, in particular, the inline six. As engine layouts go it has much to commend it in terms of refinement. No V6 can match it for balance – the term used to describe the way an engines internal vibrations do (or do not) cancel each other out. Against that is the difficulty of installing what can be a long engine with adequate space for the crash protection required these days. However BMW has kept faith with its six-cylinder engines when just about everyone else has switched to V6s.

From Fourwheelsteer: Motoring Writer
A classic BMW inline six as fitted to the M635CSi

So it was saddening to read BMW’s announcement of a new, 2.0-litre, four-cylinder, turbocharged petrol engine. It has 242bhp and 258lb.ft - more than the company’s ‘smaller’ six-cylinder engines. The new power unit is said to be smaller and lighter than the sixes too, which makes sense. It also makes sense within the context of engine downsizing that is going on across the industry for better mpg and lower CO2 emissions. BMW has already replaced the some V8s with turbocharged straight sixes. On the official mpg and CO2 tests the new engine is bound to be superior, it just seems unlikely that it will sound as good.

Incidentally, it seems that BMW’s model designations no longer enjoy the close relationship with engine size that they once did. For the six-cylinder petrol models (excluding the X versions) the designations and engine capacity are listed below:

BMW 325i – 2,996cc – 218bhp

BMW 335i – 2,979cc – 306bhp

BMW 523i – 2,996cc – 204bhp

BMW 528i – 2,996cc – 258bhp

BMW 535i – 2,979cc – 306bhp

BMW 740i – 2,979cc – 326bhp

Z4 23i – 2,497cc – 204bhp

Z4 30i – 2,996cc – 258bhp

Z4 35i – 2,979cc – 306bhp

Why, for example, is there a 3.0-litre engine in the 325i and a 2.5-litre in the Z4 23i?

Car of the Week: Volkswagen XL1 Super Economy Vehicle

From Fourwheelsteer: Motoring Writer
Volkswagen XP1

Launching an economy car in the Middle East is probably a sign of the German sense of humour but Volkswagen chose the Qatar Motor Show to unveil the 313mpg XL1 concept.

It is VW’s third generation economy vehicle and uses an 800cc turbodiesel engine combined with electric motor and 7-speed DSG transmission. It is also attractively streamlined, low, mid-engined and possibly more elegant than anything the company has built in over 20 years.

I think real world economy – as opposed to the artificial combined drive cycle – would be better with an ordinary turbodiesel engine and manual gearbox. Slightly more power and performance would be useful too; the XP1 has around 75bhp split 50:25 between diesel and electric motors. A 0-62mph time of 11.9 seconds is adequate but nothing special (although 30-60mph or 60-90mph times would be useful to know). It also feels like cheating to limit the top speed to 99mph – if the aerodynamics are that good it would be instructive to see how fast you can go on 75bhp.

I could see myself driving something like the XP1 – not something I can say about most concept cars.

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