Question/request for all you folk with trip computers

Dup said:
I drive like my pants on fire but it really ingrigues me. Much to the point of "Can I afford one" thoughts. Maybe next time.

Filled up the MX5 last night. I had done 310km (192.6 miles) and filled up with 38 litres (it's a 48L tank aparently) which makes 23.04 MPG according to the spreadsheet I've just set up. Mazda claim 31MPG combined, but with my heavy foot and a fuelish smell from the exhaust I'd say I might need to look into one of those. Still, no worse than the CTR but was expecting better.
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23MPG that's shocking :eek:

Mine's never averaged less than about 28 over a tank and that's with much hooning!

Did you brim the tank on the previous fillup? If not your calculations won't work ;)
 
Overlag said:
you have to push harder to get any movement out of it. I mean i get better MPG out of my 2litre than i did with my 1.25.... but then i rarely full throttle in the 2litre, where as the 1.25 was "flat out" everywhere.

Im currently sitting at 37mpg.
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Pumping losses are bad m'kay. The problem with little engines is the gearing TBH. Too much friction and then puts motorway speeds well away from peak BSFC's. Theres nothing wrong with running at engine closer to its design throttle opening. And of course you can accelerate larger engines whilst there still running stoichiometric rather than smaller engines stuffing fuel down the exhaust unless you are a bit more gradual in accelerating.

It is odd how this happens I agree though.
 
Jonnycoupe said:
Pumping losses are bad m'kay. The problem with little engines is the gearing TBH. Too much friction and then puts motorway speeds well away from peak BSFC's. Theres nothing wrong with running at engine closer to its design throttle opening. And of course you can accelerate larger engines whilst there still running stoichiometric rather than smaller engines stuffing fuel down the exhaust unless you are a bit more gradual in accelerating.
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Once more in English?
 
Howard said:
23MPG that's shocking :eek:

Mine's never averaged less than about 28 over a tank and that's with much hooning!

Did you brim the tank on the previous fillup? If not your calculations won't work ;)
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Yep. I brimmed it, drove 310KM where the gauge looked nearly empty and then filled up with 38L.

I've got a feeling the thermostat might be stuck open. Going to change the cooland and fit a new thermostat seeing as it's cheap and harmless. Mine is the 1.8 thugh remember.
 
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I reset my trip, mpg and average speed computer every fillup, but I've kept a log on an iphone app which calculates my mpg very accurately.

My LMPG on the Fiesta is 62mpg. Not too shabby. A few off the 67 manufacturer figure, but not dramatically so.
 
Well the guy I bought it off (first owner) left the second MPG readout unreset in all of his ownership. It was in the low 38s when I bought it if iirc. I left it the same way and it hadn't been reset in my ownership.

Also - the battery went dead on the e39 when it was outside awaiting sale and the MPG figures didn't disappear.
 
Fair enough and this didn't happen. Furthermore, there is no evidence to suggest that what I said originally wasn't correct, so why did you feel the need to correct me? Who says the ECU was reset? If I had reset the 2nd trip when I bought it, MPG would have been higher, obviously, I think I averaged about 45mpg. It's quite difficult to remember as it's nearly 2 years since I stopped using it daily.

So original statement still applies - cheers for the input.
 
05 BMW 525d, trip computer currently says 26.1, BMW say something like 36mpg combined.

Mainly as a result of short trips with lots of traffic lights.
 
commited said:
Fair enough and this didn't happen. Furthermore, there is no evidence to suggest that what I said originally wasn't correct, so why did you feel the need to correct me? Who says the ECU was reset? If I had reset the 2nd trip when I bought it, MPG would have been higher, obviously, I think I averaged about 45mpg. It's quite difficult to remember as it's nearly 2 years since I stopped using it daily.

So original statement still applies - cheers for the input.
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Is there really any need to get so defensive? I'm just pointing out its almost certain that it wasn't last reset when the car was brand new. That was some years ago now and you've no idea what happened in the previous owners tenure. Any software updates/ECU resetting/disconnects/whatever which occured when the vehicle went in for a service or warranty work etc etc would reset it, as would removing the battery.

I am also pretty certain that the CONS2 figure ONLY measures fuel consumption over the most recent 2000 mile period anyway. Either way, thats not a figure from brand new.

Keep your hair on, its not the end of the world, is it?
 
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The 2000 mile thing wouldn't make sense as I had a lot of consecutive tanks which were in the mid to high 40s (I reset CONS1 every tank, was reasonably accurate), but the CONS2 figure only crept up very slowly. My MPG only really started dropping when I fitted Eagle F1s.

I had the car serviced by BMW and again, CONS2 figure was not reset. Maybe my High OBC was magical.
 
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Major facepalm here. It doesnt get reset during a service, but if they've performed software updates, etc etc which would have happened at some point since the car was new (There are various updates earlier in the cars life), it would be reset then.

Why is it so hard for you to appreciate the chances of buying a 5 year old car which had never ever had its battery disconnected, etc etc? I mean.. lol

Maybe your high OBC was magic. Would it make you feel better if we pretended it was?

I can't confirm 100% the 2000 mile thing but I'm 99% sure its the case - its on a rolling 2000 mile basis.
 
The trip computer in my Focus is a few MPG off, it says the average MPG since filling up is 28MPG but when I calculate it myself after refuelling I get 31MPG with combined city and 50mph roads and that is a little worse than specified by Ford caused by fast overtaking :)
 
Dutch Guy said:
The trip computer in my Focus is a few MPG off, it says the average MPG since filling up is 28MPG but when I calculate it myself after refuelling I get 31MPG with combined city and 50mph roads and that is a little worse than specified by Ford caused by fast overtaking :)
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Its the same on my Fiesta. The trip computer consistently under reads by the same percentage.
 
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