Cruise Control MPG

**Phatty** · 3rd October 2008, 22:26

Just been out for a run in the new motor (v6 CDTi) and tried out the cruise control on the bypass.

i noticed that the MPG with cruise control driving was hovering 23-25 @ 70mph. Then with CC off and me driving it crept back up to 30-32 @ 70mph... this would've kept going up but turned CC back on and it started dropping again.

Is this a normal thing (maybe because the car is working harder to maintain that constant speed) ?

i won't be using cruise control too often if that is the case, especially when using Shell V-Power Diesel at 124.9p

**ditchp** · 3rd October 2008, 22:36

top gear said that CC used more fuel than normal driving when they did that london/scotland/london run a while back.....was it in a merc ???

**glynn** · 3rd October 2008, 22:41

hasn't their been a few mwmbers that have also got better mpg with cruise control on

**Caterman** · 3rd October 2008, 22:54

I told you earlier that DPF had just kicked in so it will drink like a fish for around 20 mins so take it easy for a bit

CC does seem to cause the MPG to drop slightly as it is trying to maintain a constant speed whereas a human can automatically adjust the throttle to compensate

At 70mph (without the soddin' DPF kicking in) it should be averaging around 40-45 mpg

**Phatty** · 4th October 2008, 08:50

aaahhh yes that old chesnut...

with all this torque under my right foot i'm not sure DPF will ever turn off

**ed taylor** · 4th October 2008, 09:05

The novelty of all the power will soon wear off, but enjoy it anyway. You have a nice motor there.

**Dan_BlackSRi** · 4th October 2008, 09:30

I always use my CC on my CDTi 150, and get an average of 55mpg+ for the week (over 350 motorway miles) - to be honest, never done a week of not using it though.