Downhill with cruise control

[leasaunce]

cruise control will not brake/slow down the car. didn't know the VW Polo comes with Active Cruise Control. "KEYWORD HERE IS ACTIVE"

[Y2008]

It is very possible that its engine breaking but because my feet is not busy im sensing it more. But it is extremely dependable. Car doesn't go a single km over the set speed. Thinking of it again, it does feel like engine breaking but not same way it feels when u do a downshift. It feels more like the ecu is adjusting something.

[Ben_GTI]

Okay this is what happens when you go over the westgate bridge:

You start going down with cruise control on, it uses minimum throttle (2.3L/100km), but it still starts to speed up (so tiny you can't tell), then it cuts all throttle (0.0L/100km) and the car jolts a little when it does this. That is the sensation you can feel. It does it 3-4 times coming off the bridge.

The difference between 0% throttle and minimum % seems to be larger than other cars I've had, but then again it is a smaller, lighter and a manual (no slush box to smooth it out).

[Buller_Scott]

you betcha. i did a run to and fro sydney about a month ago, lots of lovely hills approaching/ leaving sydney for the TDI to stretch her legs.

going down a hill, i deffo felto engine brako.

[mozzzy_2000]

Yeah its certianly an interesting effect but I'm also pretty sure its just using the engine to slow down much like downshifting to slow down. But when I first noticed it it did feel like braking. However you only get this effect upto a certain point. Once the incline is steep enough gravity takes over and the effect is lost and you quickly gain speed. Once that happens you realise its not applying the brakes. Would be a pretty cool feature if it did do that tho.

[mikepologti]

hmm sounds like transmission kicking into me. just gears slowing you down.

[FL00DY]

I think I might have a different opinion to what you seem to be implying ie :

It is cheaper to use only your brakes rather than your engine and gears to help slow you down.

IMHO using engine braking sympathetically is unlikely to prematurely wear out a transmission. It certainly hasn't for any of the 11 vehicles I've had for the last 37 years, and I did keep them most of them for long enough to notice if it was going to be a problem. And I don't recall any of my acquaintences needing to repair (let alone replace a complete) transmission because of engine breaking.

In fact, apart from outright abuse causing damage, the main issue I've seen with transmissions in recent years is people using top gear too much to tow heavy trailers using cars/vans with "weak" top gears (eg Turbo diesel Landcruisers, Bedford vans). Even there, it has been (admittedly expensive) bearing and shaft repairs, not totally new gearboxes.

Even VW's latest u-beaut DSG gearboxes do down shifts to provide engine braking to slow you down, so VW's transmission engineers must be pretty comfortable with the idea.

So some related questions for you :

How many examples of premature wear have you seen on manual transmissions that can definitively be blamed on using engine braking, and what percentage is that (of total worn manual transmissions) you've seen ?

How many of these have required a complete new transmission, rather than replacement/repair of the worn components only ?

OK to be honest, I've been told this in relation to driving on the track where the wear on all parts is much higher then on the road. They say it's much better at very high revs on the track when you are punishing your car to use the brakes and not the engine/transmission. So you're probably right, on the road it prob makes fark all difference.

[FL00DY]

Isnt this just abit more simple than what every1 is makin out 2 be?
When you lift your foot off the accelerator, dont you lose speed?
Thats all the car is doin in cruise control when its downhill, isnt it???

I dont think braking, electronics etc etc would come into it....

ummm you don't lose speed if CC is active and you remove your foot from the accelerator ??? That's the point of CC.

Yeah its certianly an interesting effect but I'm also pretty sure its just using the engine to slow down much like downshifting to slow down. But when I first noticed it it did feel like braking. However you only get this effect upto a certain point. Once the incline is steep enough gravity takes over and the effect is lost and you quickly gain speed. Once that happens you realise its not applying the brakes. Would be a pretty cool feature if it did do that tho.

This is exactly what I've experienced. It DOES try to slow you down, but going down a really steep hill there is nothing stopping you except brakes.