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When BMW built the M4 GTS they did rather more than turn the boost up. The car reviewers raved about was the product of changes to the power steering, the differential control, the traction control and the DCT, all of it in software, and all of it aimed at a driver on a circuit rather than one in a supermarket car park. Extra power is the easy part, and we can supply that separately. This page is about the other half, the electronics that actually make a GTS feel like a GTS.
When BMW released the M4 GTS, they made a number of changes. More aggressive engine mapping, water methanol injection, electronics upgrades, suspension tweaks…the list goes on. It’s a very, very good car. However we feel it’s a little too expensive when the aftermarket offers better solutions for a lesser cost. I mean when looking at this, we figured we’d be able to get 90% of the GTS’s upgrades in at under £10k!
We very quickly realised getting the extra power out of the engine wouldn’t be at all hard, and can offer packages up to 520BHP & 700Nm even without fitting a water methanol injection setup (Check out our case study on WMI to learn more https://www.jfautomotive.co.uk/case-studies/water-methanol-injection/ ). If we were to look at larger turbochargers, aftermarket exhausts & uprated intercoolers we could see numbers in excess of 600BHP & 800Nm.
Even with the masses of power, it just wouldn’t feel like a GTS though. That’s down to BMW’s clever electronics. The GTS was aimed at the hardcore trackday user, rather than the everyday performance BMW enthusiast. The software was designed with this in mind. Alterations were made to the power steering, the differential control, the traction control and the DCT. These are the items we’re going to be looking at today.
GTS Electric PAS Software
When driving fast, you’re reliant entirely on feedback through the steering wheel to let you know exactly what the car is doing. Whilst loads of power assistance is great in the supermarket carpark, having a very light floaty steering wheel at 100MPH+ results in a very twitchy and unstable car. The GTS PAS software dials a lot of the power assistance back at speed, resulting in much much better control & offers a more direct feel to the car.
GTS Differential Control Software
An open diff is great in the supermarket carpark, as it allows for the car to make tight turns at low speed with no excess noise. Both rear axels can turn independantly of each other…which is great until you throw the car into a power-slide, and find the inside wheel spinning up whilst the outside wheel grips. Huge cloud of tyre smoke, no powerslide, no grip…not great. Now, if you limit the amount the wheels can turn independently very aggressively, both axels are forced to share the power, resulting in superb control and a perfect drift round a corner. The car feels more stable at speed as all the power isn’t transferring to just one wheel…but when we get back to the supermarket carpark, we find the back of the car bounces and skips and jolts around as the axels need to move at different speeds to each other!
Perhaps better explained with this short video;
The differential in the rear of the M-series cars is a clever bit of kit. It offers electronicly adjustable limited slip characteristics. This basicly means, that it can change the amount of diff locking on the go. The GTS diff has the same hardware, however has a more track focussed setup. This offers much greater high speed stability, improved control when the back does finally break loose. It also makes for a much better launch off the line.
GTS Traction Control Software
On the track you don’t want the electronics pulling the power out at the first sign of a slip. This will cost valuable seconds each lap. The GTS software allows a little more slip in MDM. This makes for much more stability and safety right at the edge of the limits of grip. Traction control is more race orientated aimed at making you faster, than road orientated. A real must have for the advanced driving enthusiast.
GTS DCT Performance Software
Finally, the transmission. On the track sharper changes were required, more control over the gearbox. The DCT software offers just that, offering significant improvements in acceleration. The transmission is more responsive, and generally that bit better than on the stock car – a factory tested TCU remap. This also writes in the delightful M4 GTS exhaust burbles & crackles – giving you the GTS sound, even with a factory exhaust.
On top of these GTS updates, we’re also able to offer engine software updates, control module updates, TCS updates, HUD updates, diff updates, EPS updates, and many many more OE updates as they become available.
Photos from the build
8 photos of this BMW M2 in our Maidstone workshop. Tap any to enlarge.
Questions we get asked
What does the GTS steering software actually change?
It dials back the power assistance at speed. A very light wheel is pleasant when parking and unhelpful at high speed, where you are relying entirely on feedback through the rim to know what the car is doing. The GTS calibration gives a more direct feel and makes the car noticeably less twitchy when you are travelling quickly.
Will the differential software make the car worse on the road?
It is a genuine trade off and we would rather you knew about it beforehand. A more aggressively locking differential gives better stability, better control when the rear does let go, and a stronger launch. The cost is that at parking speeds the back of the car can bounce and skip a little, because the rear wheels need to turn at different speeds and the differential is resisting that.
Do I need to change any hardware?
Not for the electronics. The M cars already have the electronically adjustable limited slip differential that the GTS uses, so it is the same hardware running a more track focused setup. The GTS DCT software also writes in the GTS exhaust burbles and crackles, which you get on the standard exhaust.
