MPG Seems Off

[DustinIsTrubl]

I just filled up the tank on my 2021 and I drove it maybe 5 miles from there.

The MPG said roughly 60 by the time I got to work but the estimated miles left to travel says about 400.  How can that be?   It's a 40 litre tank.  It should say more.  I'm certain it normally does lol.   The cold weather shouldn't affect the estimate right?

[Kremmen]

The tank range is based on historic data as well as current

[Lord Voltermore]

I once filled up  and drove a short distance , mostly on electric. It showed 117 mpg!   But estimated range  was more realistic based on my driving pattern prior to filling up. This could have included fast motorway speeds or short journeys from cold starts.    If your next few miles are favourable for mpg it may recalculate  the range  to a higher figure.         

[coldstart]

I just filled up the tank on my 2021 and I drove it maybe 5 miles from there.
....
The cold weather shouldn't affect the estimate right?

5 miles isn't by any standard a relevant distance to gauge mpg by!

Oh yes! - Cold weather does indeed affect mpgs adversely! The shorter the distance you're driving the worse!
(and definitely also governed by your cabin air temperature setting: The higher the demanded temperature, the more heat is required - the only way the Jazz can generate heat is by running the ICE and thus burning petrol and ruining your mpgs at the same time).

All of this isn't "rocket science" but has always been the case. Only the impact on mpg is more noticable with economic cars as the Jazz.

If your car routinely gives you 25 mpg you won't worry that much about two mpg less.
But you will probably notice the difference if your car normaly gives you 65 mpg and suddenly drops to 53 mpg!
While nominally it is the same amount of petrol consumed additionally.

(if you convert mpg to the continentally used fuel efficency of  L/100km it becomes a lot more evident)

[CtrlAltDel]

In both my 2011 and 2020 this happened within a few months of owning. It tended to iron itself out over the course of a few days.

My Crosstar has gone from 62 to 54 since June . I’m weeping 😂 but really I know it’s because of the cold weather and the short drives I do.

[aphybrid]

Maybe keeping an accumulative average would indicate significant changes and also will show seasonal effects.

Attached my graphs from MK4 MPG showing apparently dramatic differences between fills but seasonal effect apparent.

Most big reductions due to high speed motorway runs between fills.

[MRCLICKCLICK]

I find that the car has to use 1 bar of juice to calculate the rest of the tank - based on the MPG etc - the first 80 - 100 miles will show an incorrect tank load - based on the previous tank usage. In winter - as the ICE is used more, even with careful driving the MPG will drop by at least 5 - 10 MPG - depend on how cold it is.

[Lord Voltermore]

(if you convert mpg to the continentally used fuel efficency of  L/100km it becomes a lot more evident)

I agree.  It makes much more sense when set to litres.  A bar rising higher from  left to right . More litres is  bad. Its often showing more than 5 - 6  litres per 100 km, quite often more than 10 litres , and sometimes even 15 or more.(18 mpg  )   All much higher than the 4 l per 100 km  or less the Mk 4 is capable of averaging. A good incentive to moderate your throttle.     In MPG its all back to front and counter intuitive. I find it very confusing and largely ignore it.
 Its a shame it cant be changed independently without also changing the speedo and other displays from MPH to KPH . 
Those in the UK should give it a try  by changing their speedo to kph for a short time.  Its quite enlightening

[coldstart]

I agree.  It makes much more sense when set to litres.  A bar rising higher from  left to right . More litres is  bad. Its often showing more than 5 - 6  litres per 100 km, quite often more than 10 litres , and sometimes even 15 or more.(18 mpg  )   All much higher than the 4 l per 100 km  or less the Mk 4 is capable of averaging.

Don't let the current consumption throw you off! As long as the ICE isn't constantly or predominantly running all is well!

This is how a hybrid vehicule is designed to run: If the ICE is running it is always kept at a fuel efficient load level!
Of course will the fuel consumption at the required load level mostly be much higher than the WLTP average.
As we all know it works out in the long run because the ICE is cut off as soon as the HV-battery is loaded and / or the power demand goes down.

What I admire most with Honda's system is that the different load levels may be heard but never felt!
The overall driving experience matches very closely that of a fully EV.