What MPG are you getting from your Mk1 Honda Jazz ?

[guest1372]

On the original Mk1 cars with alloy wheels were listed as having a worse mpg than steel wheel cars.  The rolling circumference / diameter was the same but they have a wider tread and therefore a greater contact patch.  Maybe compare a normal 26" x 1.75" bike tyre to a race bike at less than an inch wide, much much less resistance.

This phenomenon has been exploited by Volvo in the past with their V50 DRIVe fitted with ugly standard narrow low resistance wheels for testing / certification but outfitted by every dealer with smart alloys like other cars in the range.

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TG

[peteo48]

https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=175

larger diameter tyres have more rolling resistance.

Isn't the outer tyre diameter the same but the EX wheels are bigger and shod with lower profile tyres? Do the less flexible shorter sidewalls on the lower profile tryreshave more or less energy loss than the normal tyres? I can't figure out the answer from the explanation in that link.

I also wonder if the extra bells and whistles on the EX add to the weight which worsens the mpg. Are there also any extras which would worsen the aerodynamics?

On the Yaris, from what I can see, there are not that many extra bells and whistles between the Excel and the model one grade down - the Icon. You may get extras like sat nav but they are all on the infotainment type screen anyway. I wonder what would happen if you bought a Yaris with big wheels and changed them to small ones - would you then be able to claim exemption from the London Congestion Charge.

Not that I would ever be in that position but I reckon there would be lots of forms to fill in LOL.

[ondatony]

I own a 2005 Jazz with 15" alloy wheels which I have owned for 10 years. All this time, I regularly got readouts of between 56 -61 mpg on the cars computer on a regular 30 mile, mainly motorway, journey. (The highest was 66 mpg). Just before Christmas I had the two front tyres replaced with the same size and make (Yokohama), and a new battery to replace the original one! Since then the computer readout has dropped to 47-51 mpg for the same journey. Odd??

[Jocko]

New tyres make a huge difference to mpg. They are heavier, have more tread to distort (requires energy) and have a slightly larger diameter which means a taller gear. I noticed a big difference when I changed my front tyres. They will slowly improve until such time as they are due to be replaced!

[peteo48]

New tyres make a huge difference to mpg. They are heavier, have more tread to distort (requires energy) and have a slightly larger diameter which means a taller gear. I noticed a big difference when I changed my front tyres. They will slowly improve until such time as they are due to be replaced!

The ideal would be if they would stay at, say, 4mm forever!

[philiph]

My 2005 got an actual of 48.08 MPG.
The board computer said 55.38.
(370 miles driven)

Did anyone else have such a big difference?
What could be the reason for such a big difference?

Yesterday the board computer said 58.85 mpg, m/g (miles per UK gallon) and the actual was 59.74 mpg, m/g (miles per UK gallon). 141 miles driven.

Much more accurate of the board computer. I changed my driving style successfully :-)

BTW: Is it US or UK MPG in this topic?
Thanks

[Jocko]

I always use UK mpg. Most of the contributors here are UK or Europe.
That is a great mpg figure you achieved there. I cannot get anywhere near that at this time of the year.

[Jocko]

Once again, on-board display was pretty accurate. Display said 54.0 mpg and calculated figure was 53.5 (my sums) or 53.8 (Fuelly's figure).

[philiph]

This time I got 52,5 actual but the board computer was stating 57,6.

Don't know what I'm doing wrong

I do mostly highway with an occasional short city drive.

[MartinJG]

The 'fibometer' was reading 47.7 on my last fill up but just over 40MPG on the real world reading. Mainly short journeys with a bit of everything @30-70 MPH.

Edit - The latest real world MPG calculation on top up yesterday is 44.36. Think the 'dip' in MPG was down to a 300 mile round trip on the motorway. The fibometer reading has been gradually creeping down over the winter period and appears to have bottomed over the last few weeks at @47.7. The average over the winter period is probably nearer the 43-44 mark. Apply the Honest John real world metric for the MK1 and that seems about right. I did a fibometer reset yesterday and it has jumped to around 49.5. So, it seems that 'fast trip' clearly dented the overall average MPG.

[sparky Paul]

My 'fibometer' seems to have recovered its composure after fitting two new front brake calipers.

It's nice to see numbers starting with a '5' again, it was getting close to 40mpg at one point.

[Jocko]

Must have been grabbing then. Glad you got it sorted out.

[sparky Paul]

Must have been grabbing then. Glad you got it sorted out.

Definitely been binding, offside was the worst. My experience with calipers is that the only permanent fix is a full overhaul with new piston & seals. I just can't be bothered at the moment, so new calipers it is. Pattern calipers aren't that much dearer than the repair kits anyway, and half an hour and they're fitted.

I'll have to change the fluid at some point soon too, it looks lousy - despite history & invoices to say it's been changed every two years. The colour of it tells me otherwise!

[culzean]

I'll have to change the fluid at some point soon too, it looks lousy - despite history & invoices to say it's been changed every two years. The colour of it tells me otherwise!

My brothers mother-in-law had her car serviced regularly,  but when we checked brake fluid it looked (and smelled) as though it had never been changed and there was a deposit on bottom of reservoir. 

Truth is  who can you trust ?

[philiph]

Onboard display 55,39.
Actual 52,31.

After not even two months of owning a jazz i Will definitly buy a jazz over and over again. Love it.