Lotus introduced their cutting-edge Dynamic Performance Management system to the world with the launch of the Exige V6 in 2012. Developed jointly with Bosch at huge cost, it was immediately one of the most advanced systems of its kind. 3 years later, it still is.
The 2006 Elise Sports Racer was the first Lotus to come with a basic ‘on’ or ‘off’ traction control system. It was effective in reining in over-exuberance on the throttle and offered some extra security in the wet. However, Lotus insisted from the start that it was a performance aid, not a safety aid. It was designed primarily to help the car to go faster, not spare a ham-fisted driver’s blushes. That intention remains today, hence the name ‘Dynamic Performance Management’.
The man who’s done a lot of work on the system, particularly for the new Evora 400, is Lotus Cars Engineering Group Manager – Vehicle Dynamics, Ross Restell. He explained how the system works, patiently translating the myriad acronyms into layman’s English for those of us not fluent in engineer speak. His presentation from the TLF organised ‘Ten-Tenths’ day forms the basis of what follows.
Lotus DPM uses a combination of 3 key systems that work together – ABS, TC and VDC.
The first, ABS, needs no introduction but anti-lock brakes have come a long way since the 80’s. Modern cars are now able to use all four brakes independently to perform minor miracles in terms of car stability.
TC is commonly described as Traction Control but is more accurately described as ‘Torque Control’.
VDC stands for Vehicle Dynamic Control and uses a yaw sensor placed in the middle of the car to measure slip angles at both the front and the rear axles. This information is then combined with steering angle data to measure understeer and oversteer. The Lotus DPM switch allows the driver to choose the way these three key systems are combined.
TOUR mode makes full use of all of the car’s electronic systems and takes a zero tolerance approach to both under and oversteer. As soon as slip is detected at either axle by the VDC, the system cuts the fly-by-wire throttle to zero and applies whichever combination of the brakes is required to bring the car to a halt along your chosen steering trajectory. Regardless of the theory, it is deeply impressive in practice. As you’ll see on the video you can barrel into a hairpin, throw in ludicrous amounts of steering lock and stamp fully on the throttle. You can also come sharply off the throttle mid-corner, apply the brakes, left foot brake – you name it – the car simply refused to spin and didn’t even require any corrective lock. It just brings the car smartly to a halt, however much the tyres protest. TOUR is the only mode that features Understeer Recognition. However, ‘Understeer Eradication’ might be a better term. The system has been torture tested to cope with every conceivable challenge the road can throw at it, including an ECU’s nightmare of a mixture sheet ice for two wheels, dry tarmac for the others and the car has to pull-up in a straight line. It’s strictly ‘pass’ or ‘fail’ too with Bosch’s own very stringent testing standards. Of course TOUR can’t do anything about oncoming traffic, telegraph poles or suicidal wildlife but on an empty track it feels completely foolproof. One TLF member has reported that it is possible to spin with TOUR engaged – which is important to know – but the circumstances must have been exceptional based on our experience. No-one on the ‘Ten-Tenths’ day got anywhere close. In some ways, TOUR was the most surprising of the three modes for me. I had previously dismissed it as an electronic nanny, only there to comply with some piece of road safety legislation, but it’s seriously impressive to experience first-hand. The Understeer Recognition is sheer electronic voodoo. Hopefully you can see on the video how it maintains steering control and keeps the nose pointing towards the apex. Applying the same abusive driving in the other two modes results in armfuls of pronounced understeer.
SPORT allows both oversteer and understeer up to a set threshold measured by the VDC’s yaw sensor. In practice, I found this wasn’t a very large angle of oversteer, no more than a quarter turn of opposite lock in the car we were using. If you want to make the front cover of Evo magazine you’ll still need to switch everything off. Personally, I could have done with the threshold being set a little higher before the system intervenes, especially as the intervention is very obvious and not at all subtle. When the system decides it’s time to release the pent-up torque, it does so with a mighty surge. Fun, but very ‘all or nothing’ in nature. SPORT will allow the car to understeer which actually has its benefits. It’s useful for learning when you’re asking too much of the front tyres and you get more feedback from the car about your driving, which means you can still learn about how the car reacts to your inputs. It’s a great option to have and still offers a good safety net, allowing you to feel some under and oversteer without any risk of a spin. A word of warning though, given most owners opt for either TOUR or SPORT on trackdays, it’s best not to follow an Exige too closely on track. In the event of a big mistake the car will just pull up sharply in front of you rather than pirouette off into the distance (and out of your path).
So now to RACE, which is the source of all the debate and much of the confusion. In essence, RACE is a Torque Control system, designed to minimize oversteer and optimise traction when entering and exiting corners. The goal is to find the maximum traction possible for any given set of tyres and track surface, on any given day. It does this by ‘learning’ the amount of grip available. Unlike TOUR and SPORT modes which are based on fixed slip thresholds (beyond which they cut the available torque to zero), RACE manages the slip thresholds using a feedback loop between the car’s sensors. This is where it gets a bit technical but for those that are interested, when you plant your foot on the exit of a corner, the VDC estimates the grip available and allows a best guess amount of torque. If the car begins to oversteer it then reduces the allowed torque and this process continues in a loop until the allowed torque matches the available grip. At this point you have maximum possible traction. The learning process takes one clear intervention, that is, one oversteer moment at one corner – not a whole lap. But this learning process will need to be re-done at the beginning of each new session on track. The key thing to understand is that the system starts from a maximum yaw angle and torque threshold. In other words, you’re likely to experience a moment of oversteer while it learns. Thereafter, it will continue to minimize oversteer for the remainder of the session on track. In a car as responsive as an Exige, quick reactions will be needed to catch the slide, so RACE is best left to more experienced drivers. In practice, this moment of oversteer has taken some owners by surprise and caused them switch the system back to SPORT, even though RACE was just getting started! Once up to speed, the ability to adapt means that it works in both the wet and the dry and also with any combination of track surface and make of tyre. Even today, very few Torque Control systems are able to do this. The other major plus of this system is how smoothly it operates. Interventions are notably smoother than the other modes where torque is cut back to zero. With RACE mode, excess power just bleeds away, like the deftest ease back from a pro racer’s right foot. It’s really subtle and seamless in operation and any weight transfer fore and aft is supremely well managed as a result.
However, there are a few common misconceptions about RACE that need to be cleared up.
1. The system learns the grip level, not the track. It is not linked to GPS sensors or anything like that and does not require a complete lap in order to ‘learn’ the grip available on the track (unlike the driver!).
2. Race mode does make use of the brakes, particularly at the rear. Without an LSD, the inside rear brake disc is used to contain wheelspin as well as help the car turn in. This allows RACE mode to optimize traction when entering a corner as well.
3. A significant power increase over the standard 345bhp (or rather the 295lbs/ft of torque) will confuse the system. A tuned car could throw a lot more torque to the rear tyres which will actually make system intervene earlier. The VDC will think that you’re being very clumsy with your right foot and cut the torque back further than it does with a standard car.
4. RACE mode is not optimised for road use. Lotus obviously cannot recommend a system that learns through oversteer over the other two road-optimized modes. This is why the ‘ESP-off’ warning light comes on when you select RACE mode.
5. You can’t just plant your foot flat down before the apex. Without ‘Understeer Recognition’ the car will plough straight on. I tried precisely that at 4.58 in the first video and you can see the result. But once you’ve got the nose into the apex you can then floor the throttle with reckless abandon and it will fire you out of the turn.
6. RACE does still have an ESP safety-net but the limits are set high to allow the TC system to work. The car will oversteer initially but will quickly learn to minimize it.
RACE is a brilliant tool for those who enjoy their trackdays and can turn even the clumsiest lead boot into the something more like the appendage found at the end of Lewis Hamilton’s right leg. It can of course be turned off for the purists, which will always be the best choice for those who want to use their track time to learn about the car and improve their driving skill. But for going after some exotic scalps on trackdays or for setting the fastest, smoothest lap possible, RACE mode is the tool for the job. Just be ready to catch that first slide!
Many thanks to the excellent Lotus Driving Academy for a fascinating and very entertaining day. You can follow them on Facebook here. We wholeheartedly recommend their driving days and the Lotus Licence driver training, with events coming up in October it would be a good time to book. After all, as the saying goes, the most important component of any car is the nut behind the wheel!
Until then, we hope you find the videos useful.