2.0, 2.5si & 3.0si better MPG from 2007 due to new axle

R

R26Andy

Member
 Newcastle upon Tyne
I was reading an article earlier which said a new rear axle transmission was put into the cars in 2007 improving fuel econonmy and reducing CO2. Does this also mean they will have more Horse Power at the wheel?

http://www.autocar.co.uk/News/NewsArticle/BMW-Z4/227463/

"Whereas BMW's existing systems are predominantly focused around regenerative braking and combined alternator/starter motor units, the Z4 uses a new, more efficient rear axle transmission.

This 'friction optimised' rear axle lowers CO2 outputs and increases economy for all six-cylinder Z4s except the Z4M.

The 2.5si goes from a combined economy of 33.6mpg to 34.0, with CO2 output down from 202 to 199g/km. The 3.0si goes from 32.8 to 33.2mpg and 207 to 204g/km, and the 3.0si coupe from 31.7 to 32.5mpg and 213 to 207g/km.

The 2.0-litre four-cylinder engine has also been made more efficient, with CO2 dropping from 181 to 176g/km and mpg rising from 37.7 to 38.2.

The changes apply to all Z4s built from 1 September 2007"

Andy
 
You'd see just as much change using different brands of tyres, or tweaking tyre pressures more often to make sure they are optimal etc...

Very small figures. Worth having if you have them though... :)

Dave
 
Changes the Tax Category on the 2.5si as it brings it under 200gm so there is a cost saving, not sure on the others though
 
They probably just put a lower friction grease and more slippy pins in some bearings, that saves you £20 on a tax a year, but costs you £1000 every 10 years when you get premature bearing failure :wink: :lol:

Dave
 
As for your actual question, does it mean it will have more HP at the wheel. The answer is.. yes. Enough to notice? No. Anytime friction is lost throughout the drivetrain there is increased HP loss at the wheel. So this would effectively reduce drivetrain loss by a small amount.
 
Car manufacturers have done loads of things to get the CO2 down that doesn't offer any real benefit. many now put lighter oils in the engines and transmissions to reduce friction,BUT ,will lead to earlier failures due to the lower protection level they offer.Seems a crap idea but thet's the good 'ol EU for you. :cry:
 
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