[freddyq]

Hi All, just joined this forum after purchasing my i30. Great car...as you all know already 

I want to understand the fuel economy I'm getting on a trip by trip basis and initially I thought that's what the mpg figure in the trip computer was telling me. But after some reading on here I realised that the trip is showing cumulative mpg. Though that is also useful, and I reset the mpg after the first fill up (didn't brim it but I will next time after reading advice on here), I'd still like to know what the car is getting me for a single trip. If I reset the mpg reading before every trip, will that do the job? I've also got an app I'll be using to track odo readings and litres filled to give me a separate mpg calculation but again, that will only give me mpg between fill ups, not per trip.

Any help would be much appreciated!

TIA

[Dazzler]

Welcome Freddy,

No Car trip computer (including the i30 one) is that accurate. In theory, the longer the individual trip the more time the car gets to calculate an accurate figure, but still only approximate.

By doing a combination of logging your Trip computer figures and your manual calculations you will eventually have some accurate figures for different driving scenarios. Over time the economy should improve marginally and you can improve it further with hypermiling techniques which were discussed on here a fair while ago. There is plenty of discussion on the web about ways to save fuel.

These include, but obviously not limited to.. An extra few pounds of pressure in your tyres, don't cart unnecessary stuff in your car, drive smoothly anticipating traffic stops etc...

[The Gonz]

Driving style and environment make a huge difference. In Adelaide I was doing 30 km runs on a mix of 60 and 80 kph stretches and almost never anything else, across very flat terrain and, well sparse Adelaide traffic. Adelaide gave me a consistent 4.1 L / 100 km (some nerd built a fuel conversion tool on this forum for your mpg thinking).

Now in Melbourne, 3 km from work and up and down freeway ramps (yes, for part of the 3 km) and a mix of 40, 50, 60 and 100 kph and regular weekend trips across Melbourne through start-stop traffic, Firty's showing a consistent 5.7.

I've never done the brimming or logging, but I'm happy to go by the trip computer's figures more for comparison than for absolute values. However, with a lot of ~800 km trips between Adelaide and Melbourne, I know a tankful will give me well over 1100 km.

[eye30]

My car has 2 trip functions..

You can zero either one as and when you want and use it for individual trips

[asathorny]

And lets not forget that our very own research wizard (Alanho) did a very in-depth study when he owned an i30.

I am not sure if they have all been archived and also his research was for a diesel car (I think)...

As it now becomes apparent that diesels are going to be the social pariahs of the small family car world, in the UK.  I guess diesel figures will soon become irrelevant going forwards.

However I associate myself with the suggestion that you do it manually by brimming the tank then taking odometer readings, if you really want to know (roughly) what MPG your getting..

for myself I just fill the tank up and go, I mean, I have little choice whatever the figure is because if I have to be in North Yorkshire for 9:30 ready to start work, or indeed South Wales, well, I sure as hell aint gonna be getting me bike out of the shed am I...  And the cost of the fuel will go on the invoice 

[freddyq]

Thanks all for your replies. At least I've asked the question so I know for sure I'm not missing a trick. I think I will use the brimming and logging method and see what calculated figures come out.

Just so I interpret it correctly, exactly what is the trip computer mpg reading telling me? Is it the average mpg for the car over the distance covered since the trip was last reset?

[eye30]

Just so I interpret it correctly, exactly what is the trip computer mpg reading telling me? Is it the average mpg for the car over the distance covered since the trip was last reset?

last reset not the last journey

[The Gonz]

Is it the average mpg for the car over the distance covered since the trip was last reset?

Yes 

[freddyq]

OK great, thanks for confirming! 

[martyni30]

I was using the reset and fill to the top method and working it out but know I just use the fuel calculator on the home page quicker and easier on average if i'm doing a steady 75-80 mph on the motorway i'm getting on average between 52-55 mpg from my 1.6 crdi cw

[The Gonz]

I just use the fuel calculator on the home page quicker and easier

[xiziz]

My ECU seems to show about 0.3l/100km to much. My total average last year was 4.45l/100km, which seems to be ~53mpg.

Should get even better this year they are lowering the speed limit to 80kph from 90kph for the last 35km of my commute sometime this year at the cost of 3 minutes. And the engine is already run in and I'm starting to get a hang of how to drive it efficiently... And learning my commute route better, soon been working there a year, when to lift off to hit the new limit at the signs etc. Exciting times.