Cruise control doesnt like hills

[numtumfutunch]

Bit of a weird one this.......

I have a current pre facelift 5 series diesel (shh) with standard factory plain vanilla cruise control

When I approach the start of a decent gradient it initially loses 5-10mph and then gets the idea that more welly is needed whereby it then overshoots my set speed by a few mph until it settles down to whatever its been doing for the last hour or so or whatever

First world problem and everything but bloody annoying especially if Im being followed as the car behind usually has to brake to avoid nudging me up the arse

This is one of a number of BMWs Ive had going back decades and Ive never noticed this before nor have any other cars Ive had with 'standard' (eg non adaptive) cruise either

Anyone else experience similar?
Is this a known 'thing?'
Can it be adjusted away?
Any other comments?

Cheers

[E-bmw]

Not a "known thing" as far as I know.

It could be that the revs you are set at is in a bit of a dead spot, as a trial do the same in a lower gear & see what happens.

I know it would not be a fix, but at least it will tell you if that is the issue.

[Muzzer79]

Mine does the same and it drives me bloody insane.

Similarly with the speed limiter - if you’re going down a hill, it just……well, doesn’t limit your speed. It just runs over the speed you’ve set and bongs once you get a few mph over to tell you you’re going too fast.

It’s totally crap and useless for average speed zones/speed cameras, etc

I had a Merc C Class before this - you could be driving down Everest and it would still limit you to the right speed.

[mmm-five]

My F31 320D (pre-LCI) does something similar, but only in ECO mode where it tries to use as little power as possible, and allows coasting (so no engine braking going downhill).

Still get better fuel economy by not using cruise control though.

[Maxus]

That doesn't sound right. I had a G30 520d for 3 years. Covered 70k in it and used the cruise control daily on motorways. It was always absolutely spot on regardless of conditions.

Had cause to borrow a Citroen C5 this week. Cruise (when I eventually worked it out) set at 75 and speedo reads 74. Both digital readouts. I did have in mind that a German car would never show something so illogical.

[MikeM6]

I haven't had that issue with the (much older) BMWs I have had, I do however know that the braking function used to be an upgraded level of CC, so the absolute basic CC would run away down hill.

[Magnum 475]

I’ve not had the symptoms you’re describing in either my F30 330i or in Mrs Magnum’s 220i Tourer.

The only thing that gives these two a problem on hills is holding speed going down hill. In cruise control they will apply the brakes to keep to the set speed. Switch from cruise to speed limiter mode and the braking function doesn’t work, so the car will exceed the limit you’ve set. I can’t quite figure out why BMW set it up this way though.

[numtumfutunch]

Thanks all and Im now looking at Eco Pro and asking it awkward questions

The car is utterly lovely over distance and I use Eco Pro on the motorway/autobahn mainly because when I hit cancel/resume (or whatever it actually is) it gives me a more gentle nudge back up to my set speed rather than a "brace yourself Sheila" full gas acceleration

Eco Pro gets lots of bad press in other BMW bits of the web but having customised mainly aircon settings and less importantly speed thresholds I really like it especially when using CC as above

Im now back home and Denmark is a distant memory but I have a trip planned to Glasgow next month and I will explore

Cheers

[Maxus]

numtumfutunch said:

Thanks all and Im now looking at Eco Pro and asking it awkward questions

The car is utterly lovely over distance and I use Eco Pro on the motorway/autobahn mainly because when I hit cancel/resume (or whatever it actually is) it gives me a more gentle nudge back up to my set speed rather than a "brace yourself Sheila" full gas acceleration

Eco Pro gets lots of bad press in other BMW bits of the web but having customised mainly aircon settings and less importantly speed thresholds I really like it especially when using CC as above

Im now back home and Denmark is a distant memory but I have a trip planned to Glasgow next month and I will explore

Cheers

Ahhh, cruise control in eco pro mode! I understand it behaves differently in eco pro to maximise fuel economy.

Uphill the car will slowly lose speed within a set range until deciding it needs to speed up again. This works for small inclines but on a longer hill you get the acceleration phase whilst still ascending.

Downhill, the car may go into coast mode and speed above the set speed by a parameter before applying the brakes to slow.

In comfort, it maintains the speed precisely regardless of the fuel usage.

[Drmarkf]

How interesting.
I’ve just started exploring Eco Pro mode in my newish-to-me 2019 F31 320d and I’d got as far as noticing something odd was getting on with the CC-EC interaction.
So, I’ll stop worrying if something’s wrong.
Pretty dumb, though, since I bet loads of people like me would expect to use the two together on dull motorway drives…