Hi everyone.

I was wondering if any of you guys experience unintended oversteer in your Stilo?

My previous 1.6 Active Stilo used to oversteer all the time in the wet. I never drove too fast for the conditions, my other cars in the same conditions on the same roads never did it. The car even did it when it had brand new tyres all round.

I've not long bought a Stilo Multijet and that does exactly the same thing. However this one has the optional ESP system. I find that I've started to correct the oversteer before the ESP kicks in fractions later and the car aggressively lurches into line.
I know you can't turn the ESP off and that's absolutely fine, I wouldn't want to. I just find it disconcerting that the car oversteers at such low speeds. All the tyres are the same and have similar tread depth.

Incidentally I had a Fiat Panda with the optional ESP system which was almost telepathic and amazing in the ice and snow.
My other half had a Grande Punto and 500 both with the optional ESP systems, and both were crap in comparison to my Panda in the snow and ice.

Before anyone says it, I know you shouldn't rely on ESP and shouldn't drive with the mindset of it will save you.

Do any of you have ESP fitted and if so what do you think of its reactions and aggressiveness?

I've recently bought a 3-door Stilo Abarth which has ESP as standard. I think it works really well and is set up perfectly for spirited driving: it allows me to drift the car just a little, then the ESP cuts in fairly assertively to maintain that modest drift, but with a slightly oversteering attitude, which keeps the car's nose tucked into the corner. In contrast my MINI Cooper S has a real kill-joy ESP, which cuts in rather earlier!

Regarding the oversteer (rear wheels 'stepping out' too far, threatening to spin the car) my Stilo does not do that: if anything, it's inherently a bit understeer-prone, a trait that many front-drive cars suffer from to some degree - and especially ones with heavy/powerful engines.

There are a couple of quick and cheap things you can do to adjust the cornering 'attitude' of your car:

(1) Reducing the front tyre pressures by 1 or 2 psi, and increasing the rear pressures
(2) Your front wheels may be toed out too much: have your tracking checked on a proper gauge and set to between 0.00 degrees (i.e. parallel) and 0.25 degrees toe-out. My money is on this being your problem....

Also, if the front suspension has more compliance (i.e. is more willing to move) than the rear, it'll encourage oversteer. So think about whether the front springs might be tired (or even broken - a common Stilo fault), front anti-roll bar bushes might be worn, or front shock absorbers faulty.

Drive carefully after making any changes, as your car is likely to behave differently to what you're used to.

Is is also possible that you are confusing two different handling traits: (1) the inate tendency of a front-drive car to understeer as you approach the limits of adhesion and (2) the modest oversteer deliberately programmed into the ESP system, which effectively forces the car to turn into the corner (even at the limit), once the ESP system has engaged.

Thank you for replying and giving such an in depth answer.

I know the springs are OK as I've just had a major service and MOT done and they checked the car over top to bottom for me. Same with the bushes. I hadn't thought about the tracking, I think I'll get it checked.

Lowering the front pressures and increasing the rears would increase rolling resistance at the front and lower it at the rear, surely if anything that would make the oversteer more pronounced?

To be honest I used to drive my Panda on the ragged edge and the ESP cut in so fluidly and predictably, I used to take liberties because I completely trusted the system and it's abilities to save me.

I've driven and owned a lot of front and rear drive cars and I definitely prefer predictable oversteer to terminal understeer. As you've said, the system in the Stilo allows some controlled oversteer before firmly taking control. I suppose I've been so used to the ESP in my Panda and Lexus allowing me to drive on the limit with no surprises, the relaxed nature of the Stilos system will just need some getting used to.

It does oversteer at quite low speeds though and I find I'm bottling it and correcting the oversteer, just before the ESP kicks in and takes control, this then makes the car unstable as it's correcting the slide that I've already started to counter steer.

I would love to drive an Abarth, if it wasn't for the abhorrent fuel consumption I'd have one. Saying that the Stilo 150 Multijet is as fast 0-60 as the Abarth.

Samuelb86 said:

Lowering the front pressures and increasing the rears would increase rolling resistance at the front and lower it at the rear, surely if anything that would make the oversteer more pronounced?

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It's not really about rolling resistance - it's about the effect of tyre pressure (or any other variable) on cornering force and slip angle.

Cornering force is a measure of the lateral (sideways) force that the turning car generates, and that the tyres therefore have to resist in order not to slip. Slip angle is the difference between the steering geometry angle and the actual arc that the car is turning through. So, a perfect car would go round corners really fast (high cornering force) and would also go exactly where the front wheels are pointing (zero slip angle).

In reality it's a compromise, and slightly reduced tyre pressures generally give higher slip angles but higher peak grip too. Higher tyre pressures create a stiffer tyre carcass with lower slip angles but also lower peak grip.

Simply put, slightly raised pressures mean the car follows the steering faithfully, but lets go sooner: slightly lower pressures give bigger slip angles at lower speeds, but with more ultimate cornering force.

So - in theory at least - raising the rear pressures will make the rear tyres track more faithfully at intermediate speeds (which might help overcome the early-onset oversteer you've described) although they'll let go sooner as they get towards the limits of adhesion, creating a bit of oversteer on the limit - and essentially setting the car up, ready for the ESP to intervene more seamlessly.

Sorry this is all getting a bit technical!

Personally, I still think that you are describing a fairly gross geometry error (tyre pressure changes are only for 'fine tuning'), so first things I'd check are toe angle and also track rod ends, front suspension bushes (especially the big one at the back of the suspension arm, with the bolt going through it from underneath - these can look ok but actually get soft so that the toe angle changes under acceleration/braking/cornering), etc

I agree with you that the Stilo Abarth has lousy fuel consumption, although I can get 34mpg on a long run, which is better than my (slower) Alfa Romeo does! Of course, in the days before dashboard computers we didn't worry about these things, and just got on with enjoying our cars...

Thanks Alfettaman. You replied in a way that was educational and not condescending ☺ I understand better now and I'll get the tracking, bushes and track rod ends checked.

I'm always trying to get the best MPG I can and find using the instantaneous consumption a big help. I also use the cruise control a lot.
I have to say, my cars average consumption readout is nearly always very close to my actual MPG when I work it out manually.

I suppose when you've got a car like an Abarth that is great to drive, it's worth the fuel cost. My Lexus only used to do 22-24MPG but was totally worth it for the pleasure it gave me to drive

Samuelb86 said:

I suppose when you've got a car like an Abarth that is great to drive, it's worth the fuel cost. My Lexus only used to do 22-24MPG but was totally worth it for the pleasure it gave me to drive

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My thought exactly. I didn't buy the Abarth to save petrol (in fact, it's the only thing the car seems to be bad at) - I bought it to enjoy the experience - and I am enjoying it! I think what I meant is that I enjoy it more when the dashboard computer isn't constantly reminding me about the mpg 'issue'. Mind you, your Lexus makes my Stilo sound pretty fuel-efficient!

I'm lucky enough to have a really boring, super-efficient family car too, that does 65-70mpg, with free road tax, etc: If the Abarth was my only car, I think I'd be a lot more unhappy about its running costs.

Do come back and update this post when you've had the tracking etc checked - it could help other people in the future who might have a similar 'oversteer' problem to yours.