sport buttons, rev limiters and NEDC
Discussion
Lots of moaning recently about the demise of high-revving N/A engines and manual gearboxes, due to the EU economy tests. One of the problems, as I understood it, was manual gearboxes have to change gear at a set % of redline - so making an incentive to set the redline as low as possible. But a lot of cars have 'sport' buttons that change throttle response and midrange torque, and there's no obligation to have these engaged during the test - so could manufacturers set them to a different redline as well? And if so, why don't they? Maybe the EU would quickly close the loophole if one manufacturer took the piss with a v-tec style engine with a default 3,000rpm limiter, maybe there's just not a market for that style of engine anymore. Same goes for the m engines with different cold and warm redlines, does the gear change occur at different points in the cold and warm tests?
I doubt its worth it, most people would never drive the car in 'sport' mode and then would cry about having to change gear constantly and having no power. There would be issues with insurance groups too i reckon if you had a car with wildly different performance when its in sport and normal, how do you quote accurately for people that only use normal and those that only use sport etc etc.
"defeat" devices are specifically prohibited by the regulations! However, small loop holes do exist, for example, on a automated manual, if the "normal mode" (i.e. the one it defaults to on key-on) is "auto" then you can do the test as an "auto" (hence things like Vanquish/F458 all starting in Auto mode initally.
You cannot have a button that causes your car to fail the test with regard to exhaust pollutant emissions but you can homologate for Co2 under the "Normal" mode (i.e. not in sport etc)
The only signficant defeat device thatIS allowed is active exhaust systems, that have a "quiet" zone of operation which is active during the Driveby noise test. Manfactures successfully argued that this is not a defeat device because the idea of the drive-by noise test is to make the car quiet in urban driving at fairly low speed. But, by the letter of the regs, they are still a bit iffy (and infact, the EU has talked about outlawing active exhausts)
You cannot have a button that causes your car to fail the test with regard to exhaust pollutant emissions but you can homologate for Co2 under the "Normal" mode (i.e. not in sport etc)
The only signficant defeat device thatIS allowed is active exhaust systems, that have a "quiet" zone of operation which is active during the Driveby noise test. Manfactures successfully argued that this is not a defeat device because the idea of the drive-by noise test is to make the car quiet in urban driving at fairly low speed. But, by the letter of the regs, they are still a bit iffy (and infact, the EU has talked about outlawing active exhausts)
Max_Torque said:
"defeat" devices are specifically prohibited by the regulations! However, small loop holes do exist, for example, on a automated manual, if the "normal mode" (i.e. the one it defaults to on key-on) is "auto" then you can do the test as an "auto" (hence things like Vanquish/F458 all starting in Auto mode initally.
You cannot have a button that causes your car to fail the test with regard to exhaust pollutant emissions but you can homologate for Co2 under the "Normal" mode (i.e. not in sport etc)
Fair enough, I was under the impression that, for example, a manual M-car still had an M-button that changed the engine mapping, amongst other things? If so, why are these okay as surely they change the CO2 figure?You cannot have a button that causes your car to fail the test with regard to exhaust pollutant emissions but you can homologate for Co2 under the "Normal" mode (i.e. not in sport etc)
The "M buttons" etc don't actually change any of the engine operating point optimisations (in terms of fuel or ignition) they just change the profile of the driver torque demand, generally increasing torque demand at smaller throttle angles, and making it less linear (so the cars feels more "sporty" when you initialy open the throttle etc) However, to drive the emissions drive cycle, the engine still needs to produce the same output for any given part of the road load curve. so all it changes is the position of the drivers foot to make the car stay tracking the speed target trace.
The button may also change the shift points within the transmisson, but generally, for anything remotely sporty, the driving style over the EUDC is at such low rpm and load that the gearbox will always resort to "economy shifting" anyway, even with the button pressed.
For example on the Jag XFR, the "dynamic drive" setting is increased by pressing the "sport button" but if the car detects little actual "performance driving" subsequent to the button being pressed(based on steering rate, latG, accpedal rate etc) it will actually ramp back down into normal mode whilst the sport button is still pressed. (so on the road, for 99.9% of drivers, the "sport" button actually just turns on a little lamp on the dash and has no real affect on the car ;-)
The button may also change the shift points within the transmisson, but generally, for anything remotely sporty, the driving style over the EUDC is at such low rpm and load that the gearbox will always resort to "economy shifting" anyway, even with the button pressed.
For example on the Jag XFR, the "dynamic drive" setting is increased by pressing the "sport button" but if the car detects little actual "performance driving" subsequent to the button being pressed(based on steering rate, latG, accpedal rate etc) it will actually ramp back down into normal mode whilst the sport button is still pressed. (so on the road, for 99.9% of drivers, the "sport" button actually just turns on a little lamp on the dash and has no real affect on the car ;-)
Cheers, I vaguely suspected that was the case (on the grounds of it being the only consistent explanation) - so it is, in theory, possible to get an M car on it's most aggressive setting to deliver the same economy on the test as in eco-mode, you'd just need different driver input (I always assumed on something really powerful it was the opposite, with the default map making % throttle travel < % torque demand to make normal driving easier for low throttle travel, and only low-power cars would need the sleight of hand... erm... chip of making % throttle travel > % torque demand for low throttle travel) - except potentially autos, which are already covered.
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