mpg

[Millsn]

Saw a meme on FB so I've been experimenting with switching off my a/c recently.  normal mpg is 29/32, current mpg knocking on 40. Makes a huge difference. I actually find that most of the time it's not needed either. Then I can drive a bit quicker and still save! I was very surprised.

[Deano]

Your AC compressor must be some size

[gregozedobe]

That's a huge difference.

 

What distance was the 40mpg measured over ?

 

What temp do you set your a/c to ?  And what is the climate where you live ?

[SpursMadDave]

Probably more to do with actually trying harder to get better mpg than turning off the a/c. I can get close to 40mpg in my stage 2, in race mode and not using acc when I very rarely do a motorway run, and my a/c is never off. 

[DustyBones]

Yeah but then what's the point of having climate control if you turn it off and arrive at destination all hot n sweaty, or head all claggy / part deaf cos the windows have been open. Its the same as a mate of mine who had a fab super smart phone, and got about a week of battery life out of it - i was stunned he managed this until he fessed up that he had turned off pretty much every feature the phone had, thus it was literally back to a dumb brick phone, that would receive a call and that was pretty much it.

But each to their own.

 

I see high 30's out of Big Ron 👍🏼 on  most drives with no real extra conscious effort on being a fuel save dude. Generally I think the R is reasonably good on juice for a 300hp unit. So am with Mr SpursMadDave and agree a huge conscious driving effort will pull a big MPG difference, perhaps more so that knocking off the AC unit.

[golf7.5r]

General consensus for modern ac is that they eat about 3% more fuel, so that would equate to about 1 mpg at a 30 mpg average.

 

Not really noticed too much difference between the different modes personally, so I just leave it in race these days.

 

ACC on a fairly long motorway drive eats about 5mpg so I tend not to use it these days unless I'm stuck in one of those jams where you move 100m every couple of minutes.

 

7th gear in the DQ381 is effectively an over-drive, so worth around 10% extra economy on longer journeys.

 

Biggest factor, as mentioned above, is probably the drivers right foot - very easy to see 20% improvement in mpg without trying too hard.

[BenEssex1989]

Not sure it effects my mpg too much, but 1 thing I have noticed when having the air con on is the drop in power. In my old ST's and Mrs BMW you hardly notice it, but in my R it almost feels like the car is in eco mode.

[R_wannabe_owner]

5 hours ago, DustyBones said:

Yeah but then what's the point of having climate control if you turn it off and arrive at destination all hot n sweaty, or head all claggy / part deaf cos the windows have been open.

 

So am with Mr SpursMadDave and agree a huge conscious driving effort will pull a big MPG difference, perhaps more so that knocking off the AC unit.

Agree. Also IMHO, driving with the windows open is false economy and may have more of a negative effect on mpg than keeping the climate control on, due to the buffeting and wind turbulence created around the open windows, not to mention the discomfort caused to occupants of the car. Air con is on 24/7 in my car and windows always closed. 

 

I am also with @SpursMadDave and you; less pressure from the right foot on the loud pedal is likely to make the biggest difference in improving mpg. 

[gregozedobe]

19 hours ago, golf7.5r said:

ACC on a fairly long motorway drive eats about 5mpg so I tend not to use it these days unless I'm stuck in one of those jams where you move 100m every couple of minutes.

I like how ACC saves me from speeding fines/points, so I use it almost all the time on any roads that are 80kmh or more, unless the traffic is really heavy.  Most of the roads around here are fairly flat, so may not be much of a hit on fuel consumption for me (and its a price I'm happy to pay anyway).

[PeteT]

I can’t get my head round why using acc uses more fuel. Surely the gentle throttle inputs and constant speed are more economical than the inevitable speeding up and slowing down when driving without it. 

[SpursMadDave]

1 hour ago, PeteT said:

I can’t get my head round why using acc uses more fuel.

 

It doesn't! Someone started talking about acc not a/c 

 

 

[gregozedobe]

3 hours ago, PeteT said:

I can’t get my head round why using acc uses more fuel. Surely the gentle throttle inputs and constant speed are more economical than the inevitable speeding up and slowing down when driving without it. 

A good driver driving for economy can get slightly better fuel economy than ACC in hilly country because they can anticipate what is ahead (eg by allowing the car to slow down slightly as they near the top of a rise, but ACC will use a lot more throttle to maintain the set speed all the way to the top, on downhills a driver can get some "free" momentum by allowing the car to exceed the set speed, which will help lower fuel usage on the following uphill grade).  On hills my ACC will use quite heavy throttle settings if that is what is needed to maintain the set speed.  

 

In flat terrain there wouldn't be much in it, and ACC would probably do better than an "average" driver.

[NRW]

^^. 
well captured @gregozedobe

 

The ACC drives wearing heavy Safety Workboots .  V-e-r-y De-lib-er-ate-ly braking and accelerating. ☹️

[Paul 7.5R]

His very true with ACC I recently drove to Norwich from Kent with ACC but on the way home I did not use it and got better more mpg. 

[ellixtt]

Mines averaging 27 pure city driving with engine in normal mode (unless somebody wants a play 👀)

 

I use AC off and on but I’ve not noticed any change in MPG.