Diesel Help

steve-L

tony6403 wrote: »

"Overall I average 45 mpg from the ODB, I checked it twice brim to brim and it is within 1MPG...."
That sounds entirely reasonable.
And I agree with and practice frugal tactics trying to extract maximum mpg.
But forget all the distractions about 65mpg etc. when driving in certain conditions, it is the actual average, including having to drive from a cold start and in urban situations, that is representative.
The trip computers can be very misleading at times.

Actually, I think they are only misleading when you don't understand what they are measuring but once you understand they are actually very informative!

First off you need to check the overall average is actually reasonably accurate. Flow meters are intrinsically inaccurate and when you stick 2 identical ones either end of a pipe you will almost always get 2 different readings... (be it in cars, oil pipelines etc.)

Once you ascertain how accurate is is by two brim to brim fills you are set to learn about YOUR car.

My car being a pretty big and powerful 3.0L turbo made more powerful with a remap is extreme.... driven 'hard' it will get 10MPG .... I have yet to find anywhere you can drive a 280BHP card 'hard' for any length of time that is not a racetrack but.... you see the point

Driven ultra-frugally on a long motorway journey it can get 40 MPG or 65 MPG. Its up to the driver. (and possibly the fuel and service condition of the car)

Understanding HOW a diesel gets this power is key...
Despite all the fancy electronics and advances in engines its really quite simple... it does it by burning MORE fuel ... its a pretty linear equation between fuel burned and power delivered
Of course this involves preventing unburned fuel which is where the fancy electronics kick in!

So

including having to drive from a cold start and in urban situations, that is representative.

These are largely under control of the driver....
If you tend to drive to the local shop 1 mile away you will get terrible MPG ... solution is walk or if you are a 2 car family and the other car is a 1.2 petrol take the 1.2 petrol

Same goes for 'urban'... if you can avoid. (And urban includes queuing on a motorway or A road as well)

For a commute like the OP this is possibly key.... if you can change the time you start and leave work somehow .... change the route to one perhaps longer in time and/or distance

HOWEVER
When doing all of this remember MPG is not really the point, especially for the OP it is the cost of the trip that matters.

I am in a different position, MPG matters because I am paid milage for work and this is most of my milage. I get 45p/mile (under 10,0000) so if after fuel I keep 35p or 25p makes a difference over 10,000 miles!

So by using the trip computer you can learn what really makes a difference for your car! For me this has involved changing times and routes... I avoid roads with numerous traffic lights or anything else likely to cause me to need to stop and then reaccelerate so for instance routinely I avoid one route that is nominally 50mph and take one that is 40 mph because at certain times the 50mph route is all 50-0-50 and the 40 is more 40-30-40..... The 50 mph route is mostly quicker even with the stop/go but the 40mph route uses less fuel.

Equally I avoid the short route of 2 miles of speed bumps and take the longer 4 miles of A road... because 2 miles of speed bumps on a COLD engine burns way more fuel.... (according to the trip comp)

At weekends I often abandon the ultra-frugal altogether!

Flying-High_2

Are all these MPG figures quoted just from the Trip?.... If so work it out by distance covered Tank to Tank.... Then see what youre getting. I regularly see 70+mpg on my way to work but over the tankful it averages 55ish...

steve-L

Flying-High wrote: »

Are all these MPG figures quoted just from the Trip?.... If so work it out by distance covered Tank to Tank.... Then see what youre getting. I regularly see 70+mpg on my way to work but over the tankful it averages 55ish...

Somewhat irrelevant as the OP needs to reduce his commute costs to/from work...
If you set a trip after filling up the tank then measure how much you refill to the brim the next time and check MPG/DISTANCE you can see if your computer is calculating correctly... (or within how much)


(If you don't understand how the trip works and why this is different then read post above...)

jaydeeuk1

Hands up if you'd hate to be stuck behind Steve on a single lane road on the drive to work

Johnny_Barnes10

Steve I just couldn't drive like that, if I had such a powerful car. Fair play to you but maybe you should chop it in for something with better mpg?

GolfBravo

Obviously the way you drive the car has the biggest impact on the MPG. But you also need to keep in mind that you're moving over 1500kg of metal, so don't expect miracles. 1.9 TDi engine is going to use more fuel when accelerating a 1500kg Passat compared to a 1300kg Golf, for example.

You just need to check the basics:
- low rolling resistance tyres - good eco tyres can improve high speed fuel efficiency up to 10% when compared to normal touring tyres. Eg. Continental PremiumContact are notoriously bad.
- tyre pressures - over-inflate them slightly above the recommended pressure, around 10%
- servicing - is your car using lower viscosity engine oil? Is the air filter clean?
- remove unnecessary stuff from the boot
- try to avoid cruise control when approaching hills - cruise control's job is to maintain speed, not fuel economy, and it will unnecessarily apply throttle when going uphill.

The above make small incremental MPG improvements, but in the end it all adds up.

Geforce

I've got the new 116d ED which you can get over 80mpg.

Some ex-rally drivers just got in excess of 110mpg on a fairly long run (can't remember how long exactly) in the exact same car, and they were stuck in traffic at some points....
I'm not quite sure how they've managed it, maybe they pushed it whilst they were in traffic?
But what I do know is that I can easily average 60 without even trying, and over 70+ to France in the summer with four guys and a roof/boot full of kit.

Either move, or chop in your car buddy.

steve-L

jaydeeuk1 wrote: »

Hands up if you'd hate to be stuck behind Steve on a single lane road on the drive to work

Mostly you wouldn't .... because ....

Johnny_Barnes10 wrote:

Steve I just couldn't drive like that, if I had such a powerful car. Fair play to you but maybe you should chop it in for something with better mpg?

Reality wise you might .... it sounds weird until you drive something with 280BHP... and enough low down torque to move a small planet...

A couple of cars ago I had a heavily modified 306 GTi-6
Enjoying the car involved revving the ****s off it.... both pre-Turbo conversion (167 bhp) and post (something like 210 bhp)
(so similar BHP/tonne)
The 330D is completely different... whereas the 306 was fast but jerky the 330 is fast and smooth... so after a week (of OMG) its like having a bank balance in your wallet saying you have 10k in credit vs the 306 where you feel a constant need to carry round 10k in cash???
One is knowing and feeling the power is there, the other requires you to actually use it to feel it???

I just drive back from Hounslow to Woking at 19:30 leaving Hounslow and averaged (on the ODB) 50.7 MPG door to door....(which I think is quite a decent MPG from a big 3L engine) granted I only did 80 mph down the motorway but I didn't have any cars behind me the whole way.

The point is other than the sliproads the total time I could have floored it the whole journey was a fee seconds ... I could have gone from 50 to 120 pedal to the metal on the A316 becomes M3 .... then what? Keep going to 155mph??? or I could have gone from 50-80 slowly (but no more slowly than a 'eco' 1.2 thingy would at full throttle) ...

So say I go to 120 ... then what ... slow down and accelerate again for the thrill??? (rinse and repeat) Or play see if I break the 50MPG on the way home game???

My work milage is paid at .45p/mile..... it's tax free and I pay a shed load of tax.... so its worth 90p/mile in effect... and i do this 5d/week usually either Woking-Sunbury, Woking-Reading or Woking-Hounslow...

So the way I see it save the pennies over the week....
At the weekend I might go for a blast and get 30mpg.. (really impossible round here without a track to get worse on any longer journey... (though up in 'sunny Lancs' if visiting my mum there are plenty of places I can bleed fuel on single track..... )

Theoretically I could buy a 1.2 eco thing to drive to work and might get 60-70 mpg say in a tinbox that feels like a tinbox ...and then buy a Elise or S2000 for the weekend... ???

Most of my economy is actually by figuring out the routes and adjusting according to when I'm driving.... the most economical route at 08:40 to arrive Sunbury at 09:00 is completely different to leaving at 07:00 to arrive at 07:25...

And it can still be 'fun'.... the series of medium sized roundabouts on my final leg are in a 50mph zone...which I do at 45-55mph.... (that is I let my speed bleed down to 45 as I hit the roundabout while changing to 4th then give it enough gas to come out of the roundabout at 55) ....

So despite the playful

Hands up if you'd hate to be stuck behind Steve on a single lane road on the drive to work

reality is you probably wouldn't be... I did however have to pass a few cars on the 50 stretch :cool: but still got my aimed for 50mpg... and even if a car is close on my tail as I approach the roundabout (perhaps because it was doing 70 in the 50) assuming I don't need to stop most seem to disappear for a while as I accelerate through the roundabout....

If I did have a tailback start to develop ... well its only a game, I'm not unhappy to not make my target MPG if traffic conditions make me doing it inconvenience others