So it looks like farewell to Audi’s bizarre taste for overhanging engines.
If German press reports are true, which seems highly likely, bringing the future development of the MLB platform to an end signals a complete break with an engineering quirk that dates back to Audi’s roots in the Auto Union and NSU brands.
Audi’s traditional layout is a longitudinally mounted transmission positioned between the front wheels, with the engine mounted ahead of that. But while having the engine overhanging the front wheels might not have been a significant issue in the days of lightweight, small-capacity engines, it became much more of an issue from the 1980s onwards as engines got more powerful and heavier.
These natively developed Audis were for a long time roundly criticised for poor handling, poor steering feel and a nose-heavy ride - most of which was a direct consequence of having the mass of the engine in the extremity of the car’s nose.
For example, there might have been little to touch Audi’s prescient 1986 80 and 90 models, the build quality, craftsmanship and styling of which still stands today, but those heavy iron-block four and five-cylinder engines mounted in the nose were metaphorical boat anchors.
The 1994 A4 still had the same layout, but it had double wishbone suspension up front (highly unusual then for a front-drive car) and lighter V6 engines, rather than the huge in-line five-pot, and the result was far, far better. But in comparison to rear-drive BMW and Mercedes of the period, the Audi was, in terms of pure driving ability, still a long way behind class leaders.
Over the past 20 years, Audi’s A4 and A6 and related models have been improved incrementally, but the brand has resisted dropping this oddball layout. The latest version of the longitudinal set-up benefited from a slight improvement in weight distribution but remained a fundamentally dud concept from another age in automotive engineering.
It did, however, have one massive advantage over more conventional layouts. The MLB’s predecessor platforms made building a proper, full-time, all-wheel drive system exceptionally easy.
Audi’s gearbox is mounted between the front wheels, so by driving each wheel through equal-length driveshafts it was easy to add a third driveshaft - exiting from the rear of the transmission casing - to drive the rear wheels.
But even the advantage of full-time all-wheel drive is about to be dropped. The MLB platform’s new fuel-saving quattro Ultra 4x4 system only works part-time, using predictive information from the car’s surroundings. It’s amazingly effective, however, and has in effect killed off MLB’s one main advantage.
Some of you will have already noted that Subaru uses the same layout as Audi’s MLB platform. That’s true, but the big difference is that Subaru uses flat-four boxer engines, which sit lower on the nose and are only two cylinders deep. Audi’s upright four-pot engine extends rather further into the nose.
The expected death of the MLB platform does have some significant upsides. I have no doubt that a 2021 A4 based on the MQB platform will be better than today’s (very pleasant ) MLB-based car.
But it also looks like the A6, A7 and next-but-one A8 will be based on Porsche’s MSB platform. Which means a rear-drive Audi is in prospect. Who could have ever expected that?
by Hilton Holloway
18 October 2016
Poslednji put menjao Desmo
dana 22 Januar 2018, 01:47, izmenjena 2 puta