Did a long run and made over 60MPG -You have to love the economy on these cars

[bus_ter]

I did a long run last week with a lot of motorway cruising. Over 300 miles with a reported average MPG of 60.3MPG. This was also during the night, with lights on and temperatures just over freezing -so there's potential for even higher numbers.

You have all these modern engine technologies likes Hybrid power and cylinder deactivation. Yet they'll struggle to beat a 16 year old Honda Jazz averaging over 60MPG!

I'm going to fill it back to brim later and will do the actual calculation and see how close it is to the reported MPG (I expect a slight drop).

[Jocko]

That is where my Fibometer is sitting at the moment too. Been a while since I saw such a good figure. Do you reset it every refill, as I do?
Here is my best figure between top ups:

[bus_ter]

70 is incredible. I just don't get how modern cars with their improved technology haven't progressed.

Yes I always reset on fill up, and fill to the brim each time so I can do an accurate calculation if I choose.

My car has the slightly larger DSi engine. I've heard the different in economy and performance to be small.

[UKjim]

One reason why the Jazz returns such good fuel consumption is due to it's low kerb weight, most modern equivalents weigh up to 25% more and  consequently even with more efficient engines rarely better the Jazz figures.

My other car is a 2019 2 litre MX-5 RF with a 184bhp 2 litre normally aspirated engine and weighs about the same as the Jazz, on a run last week of 330 miles it returned a fuel consumption of just under 47mpg. Had this been a Golf sized hatchback with an extra 350kg on board I doubt it would have matched my figures.


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[bus_ter]

Just filled up and did the calculation.

Dash MPG = 60.2
Real MPG = 57.7

About what I expected.

[Jocko]

That is excellent. Well done.

[peteo48]

Is one big reason for mpg figures not really improving the fact that the average car is much heavier these days? Round our way, and it's by no means a wealthy area, every other car is a Chelsea Tractor.

[John Ratsey]

You have all these modern engine technologies likes Hybrid power and cylinder deactivation. Yet they'll struggle to beat a 16 year old Honda Jazz averaging over 60MPG!

Much the clever technology provides little benefit during sustained cruising at motorway speeds. My Crosstar will do better than 60 mpg but struggle to reach 70mpg at 60 mph with some of the gain due to the Atkinson cycle engine. However, the hybrid system comes into its own when the motorway gets jammed and the traffic is doing stop / start / crawl.

[Westy36]

That is great MPG, a figure to be proud of. 

To quote Colin Chapman, "Simplify, then add lightness". 

[E27006]

Our elderly cars with an engine design introduced  18 years ago, and yet they better  16-valve units in modern cars from other manufacturers.  Our elderly cars return such high mpg numbers with only an "old-fashioned"  8-valve head, Honda are the masters of engine design and manufacture. Recall the 105 mpg Insight of 2000, those cars  were measured running  at 26 : 1 stoichiometric lean burn fuel ratios.