[dazza88]

Alright guys, just a quick question. Got back yesterday from a weekend away With the in-laws, I drove my e90 330d and followed them in there peugeot 407 2.0 diesel. We sat at around 79-80 on cruise control. Now I used 3/4 of a tank and they used just under half a tank, my highest average mpg was 38.7 there's at one point was 52.3 mpg. So now I'm left wondering could it be possible there is something wrong with my car or is this the norm for a 330d auto?

Thanks daz.

[Bungle009]

Is it an LCI 245bhp. My (LCI Auto) would do 45-50 on a run at 80mph.

[doughboy]

With all due respect, (and most humble apologies if you are) are you 100% sure what the term 'average' means?

If so, what do you mean by 'the highest average' for each vehicle??

The average for the trip is what it is i.e. the average displayed at the end of the trip. Also you said 'at one point their average was 52', this doesn't mean anything either for comparisons.

You only know the average for the trip if you both reset your trip computer average MPG at the start of the trip.

If you didn't do this then the figures don't mean anything as you don't know when the 'average' period started.

When did you last reset your average MPG?

When did the Peugeot last reset their MPG?


Re 3/4 or half a tank, depend on tank size and shape of course

[dazza88]

Both average mpg readings were reset just before we set off on our trip. My final average mpg reading was 38.3 at the end of the trip and there's was 49.5

Just made me curious as to weather there was possibly something wrong with my car or is it just the fact mine is a 3.0 and there's us a 2.0?

It's a pre lci auto btw.

Daz

[philmots]

Sounds ok to me.. If it was all motorway I'd expect slightly more, assuming there was some more driving on regular roads it seems fine.

Between yours and the 407 it's not much of a difference considering your engine is 50% bigger! and automatic, and with a lot more power.

If your still concerned, check your thermostats are working correctly.

[doughboy]

OP - seems OK i'd say.

Bigger engine and power sapping torque convertor auto won't match a 2.0d manual.

The peugeot is probably lighter to boot as its built out of cardboard & recylced pop bottles (well the trim is anyway )

You could always swap!

[Dan-danGT]

Agreed Peugeot will beat it, probably on 110bhp compared with 230bhp. I had a 1.9tdi golf before I bought my 330d auto pre Lci. Well the golf was about 170hp after remap. And would get 68mpg on all motorway run. Average over a tank 42-44mpg and I drive fairly fast. Now the e90 only gets about 30-32mpg I was disappointed also but I don't do much motorway mileage well not yet. But it's heavier, more power, more doors, better car really so I can live with that.

They do seam thirsty but I think its the nature of the car, like buying a m3 and complaining fuel economy is crap.

[creepy coupe]

I blame the runflats

[lemonukas]

If its only motorway than its defiantly is something wrong. My 2.5 petrol with motorway speed at 79 mph is 39.7 mpg

[doughboy]

Originally Posted by lemonukas

If its only motorway than its defiantly is something wrong. My 2.5 petrol with motorway speed at 79 mph is 39.7 mpg

Reading instantaneous MPG on the flat, at a steady 79mpg, is nothing like the average you will get on a trip with mixed roads.

Even my 335i will do 35mpg at a steady 79 on the flat.....

[lemonukas]

Originally Posted by doughboy

Reading instantaneous MPG on the flat, at a steady 79mpg, is nothing like the average you will get on a trip with mixed roads.

Even my 335i will do 35mpg at a steady 79 on the flat.....

Easter weekend I done 220 miles with mix of motorway and Southampton city and it was ave 33 mpg

[gurpswoo1]

39MPG seems low,

I did 100 miles yesterday, I got 44 mpg average at 77mph. Oh and I have a 335d pre LCI,

[djgandy]

39mpg is low. Auto box should be fairly irrelevant at those speeds as it isn't doing anything.

[phil200tdi]

Cruise Control uses alot more fuel than just feathering the throttle to keep up with traffic.

Were you following or upfront? Did you check your tyre pressures?

I'm guessing we're talking about a 300-400 mile trip?

In any case - I'd be very disappointed!

[djgandy]

Originally Posted by phil200tdi

Cruise Control uses alot more fuel than just feathering the throttle to keep up with traffic.

Really? What is the science behind this given two journeys with the same average speed?

[dazza88]

Originally Posted by phil200tdi

Cruise Control uses alot more fuel than just feathering the throttle to keep up with traffic.

Were you following or upfront? Did you check your tyre pressures?

I'm guessing we're talking about a 300-400 mile trip?

In any case - I'd be very disappointed!

I was following and it was a round trip of around 360 miles all in but 95% of the trip was motorway with no traffic and a constant speed of 79-80 on cruise control. Also checked tyre pressures before setting off and checked engine oil level

To be honest Phil I did feel very disappointed, I really expected a bit more out of it which is why I had to ask you guys if this is normal if not what's my first port of call to check.

[Davidlindsey]

doesn't sound very good , i can get over 35 mpg easy just cruising on the motorway, infact from sheffield to nottingham down the m1 i got 40.1 in cruise at a constant 65 ish.
Having said that the difference in mpg between going a steady 70 and a steady 80 does seem large, considering your only going that little bit quicker, cruising at 90 uses much more again, i think its just wind resistance.

[Rich330D]

Hmm well at the weekend I've just done 450miles to 3/4 of a tank driving at 90mph on private roads of course officer and that was ruffly 90% motorway driving using cruise control all the time. Mines a 330D manual and remapped pushing 245bhp and 450lb torque. It was worse before I changed my thermostats hope this helps?

[parapaul]

Originally Posted by Davidlindsey

Having said that the difference in mpg between going a steady 70 and a steady 80 does seem large, considering your only going that little bit quicker, cruising at 90 uses much more again, i think its just wind resistance.

Exactly that. Resistance is proportional to the square of speed.

My signature has a fuelly link - my driving is 90-95% motorway, with cruise set at 70, never any traffic because of the shifts I work. Only once have I seen a tank return more than the average 35/36 mpg.

[phil200tdi]

Originally Posted by djgandy

Really? What is the science behind this given two journeys with the same average speed?

From Wikipedia:

Driving over "rolling" terrain, with gentle up and down portions, can usually be done more economically (using less fuel) by a skilled driver viewing the approaching terrain, by maintaining a relatively constant throttle position and allowing the vehicle to accelerate on the downgrades and decelerate on upgrades, while reducing power when cresting a rise and adding a bit before an upgrade is reached. Cruise control will tend to overthrottle on the upgrades and retard on the downgrades, wasting the energy storage capabilities available from the inertia of the vehicle.

[E92Dan]

I tend to drive faster when I'm not on cruise because I get bored. On cruise I sit back and chill out more. So for me cruise is more economical

[djgandy]

Originally Posted by phil200tdi

From Wikipedia:

Driving over "rolling" terrain, with gentle up and down portions, can usually be done more economically (using less fuel) by a skilled driver viewing the approaching terrain, by maintaining a relatively constant throttle position and allowing the vehicle to accelerate on the downgrades and decelerate on upgrades, while reducing power when cresting a rise and adding a bit before an upgrade is reached. Cruise control will tend to overthrottle on the upgrades and retard on the downgrades, wasting the energy storage capabilities available from the inertia of the vehicle.

That's talking about accelerating down hills and not up hills though. He was motorway driving, which is mainly flat most of the time. That's the same on a bike or anything, you use gravity to build momentum. The thing is you drop 20-30 mph going back up the other side of the hill, you can't really follow safely using such a technique!