Curious Acceleration Query

Fr0dders

Fr0dders

Fr0dders

Caporegime
Joined
18 Oct 2002
Posts
33,467
Location
West Yorks
We were having a discussion about acceleration over various cars at the north york moors meet and we were comparing the performance of the e46 330i and the Z4 3.0i and commenting that obviously being lower weight the Z4 would be a bit faster. We then speculated on just how much quicker the Z4 M would be with the m3 engine on board.

so why then does autocar reckon the E46 m3 is quicker than the Z4m ?

Heres the Data

http://www.autocar.co.uk/CarReviews/RoadTestsData/BMW-Z4-3.2-M/221602/

versus

http://www.autocar.co.uk/CarReviews/RoadTestsData/BMW-M3-3.2/176639/

Same 346bhp engine, same 2nd,3rd, and 4th gear ratios

but its 1577kg plays 1495kg

yet the M3 is quicker on 30-70 in gear and 0-60 as well. AND its the heavier car

huh ?
 
One thing Autocar miss on the online version of the road tests that you get in the print version is the track conditions when they do the timing. It's probably as simple as the track being soaking wet when the Z4M was tested yet bone dry with the M3.

Perhaps also the lighter rear end of the Z4M provides a few traction issues, I certainly notice its far easier to spin the wheels up in the Z4 3.0 than it is in my 530i which has presumably more weight over the rear wheels.
 
Note that the Z4M isn't much lighter than the e46 M3 - there's only about 50kg in it.


Edit, oh you've already looked :p. The M3 is probably better at getting its power down - the Z4m is well known for being a bit lary.
 
Last edited:
makes sense

its why the VXR8 bathurst has such poor times. It spins the wheels in 2nd and 3rd if your floor it without sympathy. Its not nearly as fast as the 600bhp headling would make you believe.

NickXX said:
Note that the Z4M isn't much lighter than the e46 M3 - there's only about 50kg in it.
Click to expand...

indeed but you'd expect the z4m to be quicker, but not by much.
 
Like Fox says; were the times recorded on the same day at the same location by the same test driver????
 
wez130 said:
how was british superbikes pete?
Click to expand...

Pretty good yesterday and for the practice this morning. Just as the first race was about the start the camera broke again dishing out Error 99s. Got annoyed with it at went home as I knew i'd be watching some epic action and not being able to get some decent shots.

Not happy with the repair people as they've probably bodged the repair so i'll be on the phone with them tomorrow.

Sorry for hijack MrLOL ;)
 
Possibly down to the Z4MC having a higher drag coefficient than the M3. Although owners who have switched from the M3 to the Z all say the Z4 feels quicker, in reality there's nothing in it.
 
Is it exactly the same engine though, perhaps they have given the M3 an edge by fitting some wilder cams then the "M" engine in the Z

Note the torque output between the two ;)
 
Was gonna say, is the torque output the same? Such similar cars I would put down entirely to the driver.
 
You say the gear ratios are the same (this will be the case, as most BMW 6-spd boxes are the same), but what about the final drive ratio in the diff?
 
Final drive ratios are the same, but the M3 has a higher ratios 1st, and lower ratio 2nd gear, i.e. 1st and 2nd are closer together. The M3 also has ~3.9% overall higher gearing due to the higher profile rear tyres (255/45R18 compared to 255/40R18 on the Z4).

There is also no aerodynamic data on either car to compare e.g. CdA
 
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