Worshipping a False Idle
Regarding cars shif ting to neutra l when in overrun, issue 432, the DSG in my 2018 Golf R will do exact ly t hat in ‘Eco’ mode. It is however, lightning quick to re-engage drive when t hrott le applied. Modern trannies are magic !
Love the mag and your section in it, Morley. Keep it up. Chris Baksa,
Morley Says...
YEAH, THIS is starting to look like a trend, isn’t it Chris? Seems like this behaviour in auto trannies is pretty common, but one of those things that you only notice once somebody has pointed it out to you. Mind you, the DSG in your VW is a totally different animal to the old-school torque-converter auto that kicked off this discussion, but the theory about decoupling to save fuel still holds water.
I did get a follow up letter from Paul Burge (the bloke who originally noticed this behaviour in his cars) who wanted to clarify the point that his cars only dropped revs momentarily and then the revs bounced back even before he’d given it a little throttle after coasting. But even so, I reckon we’re talking about the same thing here, and it’s all down to the car’s brain trying to minimise the fuel burnt and the emissions emitted. Even though your car with its double-clutch box (a robot-controlled manual, fundamentally) only picks up revs once you’ve applied the boot, I’m sure I’ve noticed conventional autos doing exactly what Paul has noted in his letter that kicked this whole discussion off.
And while I agree with you, Chris, that modern transmissions are great at saving fuel and improving driveability, but I still have old-bloke concerns about the whole double-clutch gearbox phenomenon. As in, I reckon it could easily turn out to be a technological blind alley.
Efficient though they are, these transmissions are expensive to build and they don’t all seem to have the life expectancy enjoyed by the rest of the modern car. Plenty of these things have suffered terminal reliability problems and can die very young with clutch packs wearing out and bearings giving up the ghost and leading to a complete meltdown. And you better believe they cost an arm and a leg to replace.
Ford found out about this the hard way with its own double-clutch Powershift (silent `F’, apparently) gearbox in Fiestas and Focuses. Mainly when the ACCC stepped in, fined the company a bazillion dollars and accused Ford of `unconscionable conduct’ which is a two-dollar way of saying: You done messed up, boy.
But even if the durability bogies can be fixed (and Porsche seems to have got the concept right with its PDK version of the tech) the rest of the transmission world is catching up. While the double-clutch was born out of motorsport where lightness and shift-speed are kings, modern torqueconverter autos are more compact, lighter, have lots and lots of ratios and
can shift much faster than ever before. And they’re relatively cheap to make. Compared to a DSG, anyway.
Oh, and I just read a yarn where VW is looking at a brand-new family of conventional manual transmissions for pretty much every front-drive platform it plans to make. The manual once looked like it was on borrowed time thanks to emissions targets where the humancontrolled manual was dirtier on each gear-change compared with a robot controlled auto. But thanks to hybrid drivelines and the emerging all-electric car which has no tailpipe emissions at all (obviously) the manual could re-emerge as a dead-set force in car design. Lord, let’s hope so.