High Speed Instability in the Z4 Coupe, Is it normal?

J

jza

New member
Hi,

I'm new to this site and have been having a few concerns with my Z4. Basically I bought my new z4 Coupe 3.0si around a month ago and it has only done 2000 miles, however I have noticed the car is very twitchy when you are travelling at motorway speeds or above. Previously I owned a BMW 118d MSport and it seemed much more stable at the same speeds. I am wondering whether it is a problem with car or just a characteristic of the z4. Coming from only owning diesels to 6 cylinder petrol means that sometimes I find myself revving the car quite hard just to hear the beautiful noise it makes, so sometimes I end up doing quite high speeds.

Just to give you more of an insight into the problem, the car seems to dart around quite a lot, a right handful, and generally unstable over bumps or dips in the road, this could be due to the stiffness of the suspension setup but I just want to be on the safe side.

Any advice would be greatly appreciated.
 
Welcome to the forum :thumbsup:

I find it quite stable - though mines a roadster....

Could it be tramlining? Mine used to do that quite a bit and was startling - went away with a change of tyre brand :D
 
What do you consider highway speeds? I've run mine, cruise control on, at 80 or so with no problems. Those wide, run flat tires will tramline a bit if the road is rutted.
 
It can be quite bad if you've still got the original run flat tyres on. I found driving on the motorway in the slow lane when trucks had made deep ridges, it was quite alarming, like driving a bob sled at times. Some country lanes could be a little hairy at first too but it was easier to get used to that.

Things are much more enjoyable with regular tyres.
 
Hi jza - welcome

Aside runflats, which due to their structure tend to be worse on tramlining, stiff suspension (especially the ///m sport option) the fairly light weight of the car, much wider and low profile tyres and more responsive steering, greater driver involvement and many other factors, it can feel rather 'lively' to some as it seeks every opportunity to follow a rut, bump or white line. To those having come from a saloon car with it's more predictable characteristics it can seem rather alarming, but unless you have reason to supect something is wrong it's likely perfectly normal.

I have been to very high speed and it's rock solid steady and instills total faith by providing that very feedback that you refer to a 'twitchy'.
 
Welcome Jza!

Mine used to worry the hell outa me too but over time and a few thousand miles it has certainly got a lot better, plus I'm more used to it.

Having said that, have you checked you tyre pressures? Mine started tramlining badly again after I had new wheels fitted under warranty at the dealers, turned out the tyres were inflated to 52 psi! Once down to the correct pressures it was miles better.

If you're still not convinced, try and get a drive in another Z4 coupe to see if its any different.

Best of luck!
 
Hi,

Thanks for all of your replies. I took the car back to the dealership today to have a rattle in the door sorted out; while I was there I took one of the mechanics out to show him the problem I have been having at high speeds. He told me exactly what each of you has said that the nervousness of the car was due to a number of factors, namely, the lightness of the car, stiff suspension setup and the run-flat tires. He assured me that it was nothing to worry about and that if I had been given any other z4 Coupe it would be the exact same. I'm very relieved that there isn't a problem with my car and that I just need to adapt my driving style a little bit when driving at those speeds. I will take your advice and probably go with non- RFTs next time, or at least change the brand of tire. I had Michelin PS2s on my old E46, maybe they'll be the best option but I've still got a good few thousand miles before that.

Once again thanks to all of you.

Jza
 
takes a bit of getting used to but is weel worth it. Herminator what you doin in the slow lane? !
 
paddy wright said:
takes a bit of getting used to but is weel worth it. Herminator what you doin in the slow lane? !
Click to expand...

errr.. about *ahem* mph :P :evil:

The M1 is occasionaly clear enough up near Newcastle and I hate middle lane hogs :fuelfire:
 
glad you are happy now, must admit Im not a fan of run flats, just ticking down the days until I can change all four tyres... that said you do get used to it, just driven to France and back in my Z4 coupe and loved it... retro fitting cruise control was well worth the cash too :)
 
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