Over 60mpg at 80mph on cruise contol??

[bassman]

If you've read some of my previous threads, you will know I check my mileage brim to brim every week....

Before my MAF failed I was regularly getting 50mpg on day to day journeys and maybe 54mpg on runs...(cruise control 70mpg)

After a T4 test(by MarinaBrian) and watching my MAF failing, I got the XPower upgrade done...taking the BHP upto 131.....

Initially I saw no difference in acceleration, but hoped this was down mainly to running without a MAF....

My new MAF arrived and is working great, but can still not see any definate increase in power, but have decided this may be down to my very economical driving and rarely getting over 3000 revs...

Yesterday however I got a bit of a surprise....I had done about a 100miles since my last fill up and OBD reset, and my MPG was reading 48.7mpg(its now very accurate)...I travelled 20miles down the A19 at 62mph(according to speedo) using cruise control, and when I turned off the A19 after the 20 miles...my OBD was now reading 51.4mpg.....gone up due to cruise control driving...I drove home a different way and on reaching home, it had dropped again to 49.7mpg....

An hour later and being in a rush, I did the same 20 miles, but this time I set my cruise control at 80mph, and when I turned off 20 miles later my mpg had gone up tp 59.7 mpg......

with already having 120 miles on this tankful at an average of 51.4mpg...to get it upto 59.7 must have meant I was getting well over 60mpg on that final 20 mile stretch....

After running around town today its back down to around 51mpg...

As I said...I check my mpg every week using brim to brim, and the minimum I ever get is 49mpg...

Could the increase at 80mph, be down to the XPower upgrade, as Brian said I would only feel the benefit of it at higher revs.........or when towing my caravan(which I havent tried yet...)

[T-Cut]

Originally Posted by bassman

Yesterday however I got a bit of a surprise....I had done about a 100miles since my last fill up and OBD reset, and my MPG was reading 48.7mpg (its now very accurate)...I travelled 20miles down the A19 at 62mph(according to speedo) using cruise control, and when I turned off the A19 after the 20 miles...my OBD was now reading 51.4mpg.....gone up due to cruise control driving...I drove home a different way and on reaching home, it had dropped again to 49.7mpg....

I think you've probably answered your own question in regard to the diagnostics screen. Resetting the computer severely limits the data it collects before you display the calculation. The more often you reset, the less accurate is the display figure (as a long term average figure). If you read through the diagnostic mode write up, it advises you to not reset the computer too often. In fact it's better to never reset it. Your greatly varying consumption figures confirm that you have reset the system too recently/often and produced a significantly over-optimistic result. The fact that the system has been accurately calibrated won't alter this anomaly.

EDIT: Your excellent consumption figures were probably accurate over the particular time frame involved. As you integrate slow traffic/town driving conditions, the display will begin to integrate these situations into the calculation and it will become the 'true' average consumption figure. Here's what I mean.



This was my 1.8T just after a reset and brisk acceleration. It's meaningless.


TC

[bassman]

Originally Posted by T-Cut

I think you've probably answered your own question in regard to the diagnostics screen. Resetting the computer severely limits the data it collects before you display the calculation. The more often you reset, the less accurate is the display figure (as a long term average figure). If you read through the diagnostic mode write up, it advises you to not reset the computer too often. In fact it's better to never reset it. Your greatly varying consumption figures confirm that you have reset the system too recently/often and produced a significantly over-optimistic result. The fact that the system has been accurately calibrated won't alter this anomaly.

TC

I agree with all of that........if I wanted a long term average figure.....but when I fill up and do a brim to brim, the figures represent what mpg I got from that last tank, and thats why I found they didnt agree with the long term average...

Doing it this way and resetting it every week, I can actually see what mpg I got from the last tank, and the results are surprisingly accurate.

I think I prefer to see what I am actually getting, than seeing an average as tbh,I strive to increase my mpg all the time, so seeing the mpg rise, by say....making sure its in 5th gear(at <900rpm) on an urban 30mph road rather than leaving it in 3rd(1600rpm) or 4th(1100rpm)....gives satisfaction

If I want an average I just look at all my previous weeks....

I pleasure drive around 400 miles a week(or more) 99% of the time, never having to rush...

Unfortunately Ive possibly become one of those drivers I hated 40 years ago......

re your addition....

Is it meaningless though..............If you continued that same acceleration constantly, maybe you would only get 7mpg....Its a bit like going down a hill after resetting it....Ive had the OBD read 342mpg.....but i suppose if I always travelled down hill......I may get 342mpg......

[NigelOBB]

Totally agree TCut last month I have averaged around 38mpg mainly round the doors a 60 mile round run to Darlington and a couple of trips to the metro centre working out using the brim to brim method that's with a dodgy thermostat trip shows 27.9 over 1200miles

[bassman]

Originally Posted by NigelOBB

Totally agree TCut last month I have averaged around 38mpg working out using the brim to brim method trip shows 27.9 that's with a dodgy thermosst

Sorry.....but I just cant see your point here........or any relevance to either posts..

[NigelOBB]

Sorry mate meant to add when I first reset the obd trip it showed a more real time view of my mpg and would drop to 20mpg round by the end of month the longer I left it the average mpg took long to change as it settled.. But it's still not a true reflection of what I have used when I worked out my mpg on actual fuel used

[T-Cut]

Originally Posted by bassman

I agree with all of that........if I wanted a long term average figure.....but when I fill up and do a brim to brim, the figures represent what mpg I got from that last tank, and thats why I found they didnt agree with the long term average...

Yes, you're right. If you want to know how far every tank takes you, you're doing it right. Calibrating the OBD calculation is critical to this, but the calibration only represents the sort of driving you were doing when you generated the calibration data. So, you need a calibration set for each type of driving style you contend with. It's quite likely that a calibration based entirely on driving at say 80mph using cruise control would show that every time you drive that way your consumption figure is quite amazing - compared with the figures others quote for 'average' driving. At the end of the day, it all depends on what you mean by - - -.

As a matter of broader interest, what does the OBD say about your typical running temperature?

TC

[T-Cut]

Originally Posted by NigelOBB

Sorry mate meant to add when I first reset the obd trip it showed a more real time view of my mpg the long I left it the average mpg took long to change as it settled.. But it's still not a true reflection of what I have used when I worked out my mpg on actual fuel used

If you calibrate the computer's calculation factor as discussed here and use that as your long term (average) consumption base, you'll find it works very well. However, the system can be used in different ways depending on what it is you want to know about fuel consumption, i.e. per week, per month, per year or even per tank full. The important thing is the calibration must be determined using the journey/driving style you intend to do over the period in question.
The alternative is garbage in, garbage out.

TC

[NigelOBB]

I've been messing with all method and I think have found just to leaving it seems to be working the best..for me.. I have always work out my consumption after a top up.. Even if it is only twice a month ..😃

I've tried to access the obd diagnostic display but can't catch it right. I'll ask at the next MetroCentre meet if someone can show me ..

[James.uk]

I recall there was a bloke in the USA who was obsessed with getting max mpg from his Honda ... He got himself banned from driving in the end I think.. Called Wade something??? I think he caller himself a "hypermiler" or something silly...
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