MPG for those interested

[Kremmen]

That still doesn't compute v the onboard calculator.

Last time I heard of such a discrepancy was a son siphoning a few gallons out when dad wasn't looking.

[Jazzik]

I am (more than) a little surprised when I read above that cee drives 380 miles on a full tank. ⛽
Is that the same Honda Jazz e:HEV as mine?
I see significant differences in fuel consumption. Some here seem to have a significantly higher consumption than I do, others rather comparable.
So far I have an average (measured) consumption of 62.9 MPG.
I drive normally, not like a nearsighted grandpa but also not like Max V., always in Econ and B mode (except on the highway with ACC). Heating and air conditioning are used as needed.

I've never refueled after less than 386 mi (that was 5.72 Imp.gal), but I normally do between about 420 and 490 miles on a tank of fuel.
The last fill-up was in mid-January (Winter in Poland!) after 435 miles traveled, a fill-up of 7.15 gallons (60.8 MPG).
In the fall, I filled up 6.90 gallons on Oct. 8, after 487.8 miles: 70,7 MPG (80% local roads with a max speed of 90 km/h = 56 mph and 20% city traffic).

Why do I see here such (rather significant) differences?

[guest9814]

6.25l/100km is too much, how that can be done ?
Maybe short trips with climate control set to 25 degrees C ?
Or even worse case short trips with climate control set to 25 degrees C  on highway with fast acceleration and hard braking afterwards.

[sportse]

Cruising at 70mph/110kph I’ve found I get 50mpg, it doesn’t matter if I accelerate slowly or  don’t brake/use B/ use eco mode - I still get almost the same 50mpg.

However as soon as I drop below 50mph I’m getting nearer 70mpg. Either roadworks on the motorway or country roads.

There’s not much the hybrid system can do to save mpg for hours of 70mph constant cruising unfortunately.

It’s the same with pure EV cars - as soon as you add high speed cruising into a journey your range drops massively.

Some good information on real world EV motorway ranges in this review - it’s the same for the Jazz and other hybrids.

[peteo48]

Yes - I've said this before but if you look at Mk4s on spritmonitor there is a huge range of mpg figures. The way I see it is that it is possible to achieve superb mpg figures but this almost certainly requires a particular driving profile. On a warm day, doing a decent mileage on a mixture of town roads with some country roads in the mix it will be possible to top 60 mpg - maybe even better.

This can lead to disappointment so the more relevant metric for me is what my previous (non hybrid) car did. I am disappointed that I can't join the 60 mpg club but I'm bumping along at just over 50 mpg at a time of year where my Mk3 would have been doing late 30s/early 40s at best.

[cee]

Hi Guys, i do understand differences in MPG we are all getting but what baffles  me is the discrepancy between MPG on the trip computer vs miles per tank. Can you let us know how many miles are getting from the full tank please?


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[Jazzik]

what baffles  me is the discrepancy between MPG on the trip computer vs miles per tank.

I keep track of my consumption on Spritmonitor https://www.spritmonitor.de/en/ , where you note the actual amount of litres/gallons fueled and the number of kilometers/miles driven.
In addition, you can also fill in what the on-board computer indicated as consumption (plus additional information that you want to add yourself).
I have kept track of that and the conclusion is that my actual consumption so far is about 4.5% higher than what my on-board computer indicated.

[Kremmen]

Those figures are so adrift I'd be getting the dealer to check for any fuel leaks.

[sportse]

Hi Guys, i do understand differences in MPG we are all getting but what baffles  me is the discrepancy between MPG on the trip computer vs miles per tank. Can you let us know how many miles are getting from the full tank please?


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It’s a 40 litre tank I believe, at 50mpg if you ran it completely empty theoretically it would give a 440 mile range vs the 380 miles the range meter says.

Most cars have a reserve of fuel when the range says zero, so that works out at around a gallon or so.

[Lord Voltermore]

Hi Guys, i do understand differences in MPG we are all getting but what baffles  me is the discrepancy between MPG on the trip computer vs miles per tank. Can you let us know how many miles are getting from the full tank please?

Sorry, I missed your main concern. I think you accept its possible to get less than 50 mpg in unfavourable conditions such as high motorway speeds,short journeys etc  . ( My car has averaged about 65 mpg over 2000 miles, but even so there are times when the constant fuel consumption bar is in the low 30's.mpg. Get this too often average consumption plummets )

But the discrepancy in on board computer figures does seem excessive.   Maybe the calibration is wrong. I'd think  a physical fuel  leak, or mechanical problem increasing fuel consumption is less likely. Wouldnt you smell fuel or notice poor running? 

Not sure exactly how it works, but I'd have thought part of the system would measure actual fuel flow to the engine.  If this increases,for whatever reason,it should still  register as fewer mpg.
But I may be wrong.  The system may only estimate fuel consumption based on engine running time, throttle settings, load ,temperature etc.
Either way its probably a good idea to have it checked by a dealer.

[culzean]

Not sure exactly how it works, but I'd have thought part of the system would measure actual fuel flow to the engine.  If this increases,for whatever reason,it should still  register as fewer mpg.
But I may be wrong.  The system may only estimate fuel consumption based on engine running time, throttle settings, load ,temperature etc.
Either way its probably a good idea to have it checked by a dealer.

Normally the ECU keeps track of the injector 'on time' - which is the amount of fuel squirted into engine,  if the fuel pressure is constant then the amount of time the injector valve is open can give the volume of fuel used.

[sportse]

When I picked up my car from new with only 8 miles on it and it’s first full tank of fuel, the fuel range remaining was over 600 miles!

I’ve never seen anything like that again, not sure how the computer managed to get a figure so high with so few miles.

[Kremmen]

Mine still shows just north of 600 each fill up.

[John Ratsey]

When I picked up my car from new with only 8 miles on it and it’s first full tank of fuel, the fuel range remaining was over 600 miles!

I’ve never seen anything like that again, not sure how the computer managed to get a figure so high with so few miles.

The engine was already warm when the car returned from getting the tank filled and it might have been a slightly downhill journey as well.

I keep a record of the car's claimed mpg as well as what I calculate from fuel into the tank. The car is averaging about 4.5% high.

As already noted, cold weather and short trips are an mpg killer. I always have trip mpg showing on the big screen and this highlights how the mpg improves from a low start. I keep the heating off until the engine is warmed up which means several miles (that's probably why Honda gave us heated seats).

[Kremmen]

My actual, miles covered v squirt put in is calculated via Spritmonitor, under my avatar.

Currently 61.3 but I reckon that will increase at it warms up, depending on AC power.