What MPG/Mileage do you get in your car?

steve-L

djgandy wrote: »

50mpg @ 100mph? Extremely unlikely considering there is 4x the amount of air resistance alone at this speed vs 50mph. Maybe down hill you'll get this.

I'm going to retry.....

Issues to testing though are:
1) I have to rely on the ODB reported figures and though I know this is quite close brim to brim (1MPG max difference when tested 2x) I don't know the sampling and algorithms used.

The ODB has lots of possible inputs,
Example copied and pasted

4 Momentary Consumption
4.0 0145+ Instant fuel consumption - 0145=14.5 liters/100km
4.1 0018 Instant fuel consumption - 0018=1.8 l/Hour
5 Distance Gone Consumption
5.0 082 Average mileage; 082=8.2 liters/100km
5.1 0536 Calc. km to refuel (momentary distance to go)
6 Fuel Level sensor inputs in liters
6.0 109330+ Fuel level averaged; Left half sensor input=10.9 liters; Right sensor input=33.0 liters
6.1 0439+ Total tank level averaged; vlgs 6.0: 10.9+33.0=43.9 liters
6.2 0442+ Indicated value (44.2) and tank phase
7 Temperature and Speed
7.0 021+ Coolant/Engine temperature (2.1C)
7.1 130 Ambient/Outside temperature - chg met 5 pts. 125/130/135
7.2 + Engine speed / Current RPMs 1/min
7.3 + Vehicle speed / Current Speed in km/hour

etc.

Hence I expect that some averaging algorithms are used that account for the accuracy of different sensors..... (I know a lot about this in a non car context and wouldn't expect the requirements to be that different)

Hence this all goes back to the ODB, how long a sample I need and keeping the same conditions....
the nearest place I could test this is a couple of miles away but I somehow doubt Mercedes are going to let me use their test track

Also, there are a few reasons REAL WORLD figures are different to TESTED....
One reason is obviously the manufacturers would want to report the best figures but its really more complex.

If you measured this over any reasonable distance, how do you keep the environment constant? Air resistance isn't constant if the wind is blowing with you or against you....

What does MPG at 70 mph (or 55 mph) mean?
Other than a rolling road what do we mean by 70 mph? Do we mean 'between 69 and 71' or 'between 69.9 and 70.01'.
In other words if the speed drops at which point to we apply gas and how much (how quickly to we aim to be back inside tolerance).

My subjective observations relying on the instantaneous MPG are this makes a HUGE difference....
Say I allow myself a speedo reported 68-72 .... I can either wait till it drops to 68 and then floor it for 1/2 sec (at say 10mpg) or apply incrementally a tiny amount of force to the accelerator... or wait until I'm going slightly downhill.....

The differences are HUGE according to the ODB ....

Even in the Honda with no MPG display I did a 300 mile+ test.... my partner driving got 25% LESS on motorway driving (in better conditions)

Brim to brim the BMW 330 gets similar to the Honda 2.2... but has DOUBLE the max BHP..... so I 'assume' the possible MPG differences based on driving style are even BIGGER than the Honda....

I also noticed lower MPG approaching oil change AND switchover to Winter Diesel .... but of course that could also be driving style?

Gloomendoom

steve-L wrote: »

Brim to brim the BMW 330 gets similar to the Honda 2.2... but has DOUBLE the max BHP..... so I 'assume' the possible MPG differences based on driving style are even BIGGER than the Honda....

They will be. It's acceleration that kills mpg and the faster, and more often, you do it, the more fuel you will use.

Elliot_N

I drive get 55mpg reliably out of my 1996 Golf TDI (best car I have ever owned) and I get around 11mpg out of my VW Corrado 16v Turbo

kkgree1

Currently 44.6 mpg from a 18 month old 1.2 Ford Fiesta Petrol.

Does a mixture of A roads and city centre driving normally. Can get nearer 48 - 49 mpg if motorway driving.

steve-L

Gloomendoom wrote: »

They will be. It's acceleration that kills mpg and the faster, and more often, you do it, the more fuel you will use.

Yep so my big question is how much.....

If a give it a tiny but extra vs a bigger bit.
I see quantum changes on the instantaneous MPG..... it might jump from 55 to 30 or 55 to 45 .... but obviously running at 45 for longer then returning to 55 would be the same as running at 30 mpg but for a shorter time....

Overall, partly obviously a bit longer for 30 is better than shorter at 45... (and there are other things like approaching hills or stops to take into consideration) but then the question is HOW MUCH overall does it affect the MPG.

To turn this around..(as a thought exersize)... if I was to drive exclusively using the MPG to guide me and basically try and get absolute max MPG regardless of when I arrive or how pleasant the drive is then HOW MUCH difference might it make?
If this is £52/yr I personally am not interested .... if its £5200/yr I am and in-between.... ?????

One thing I did realise is that other than the 'fun' from seeing just what MPG you can get it's 'unpleasant' driving at the extreme....

Driving from Poole to the end of the M3 at an average 68MPG (according to the ODB) was really quite a challenge just staying awake.... even planing how to use the approaching hill to advantage or slipstream the lorry ....

On the A roads it involved timing each roundabout to avoid losing momentum... on the motorway it meant overtaking even if I was only going 1mph faster .... so as not to waste momentum and have to touch the brakes and lose/waste kinetic energy...

Obviously there is a happy medium, what I'd love to know is just how to find it!

sam959

I get about 25 - 32 MPG out of my Civic type r! I don't care though!

UsernameAlreadyExists

I get ~24 MPG Average (according to trip computer) in my daily use ST220 estate.

I've had it edge a little over 35 MPG on a good long motorway cruises though.

I dare not even think about the MPG on the weekend toy. That'll possibly be below 20

sam959

Thats good going! My car is to rev happy to get that! But i do love hitting the vtec sounds nuts! Its the tires that cost me money i get through a set every 6 months Nevermind she never lets me down so its worth it!

Cornucopia

I tend to use cruise control on longer distance drives.

My logic is this: the type of cars that I drive give their best MPGs on this type of driving (60-80mpg), and I do not have the patience to drive frugally for hours on end, therefore if the CC is 10% less efficient than the theoretical ideal, it is still better than I could manage myself.

But, what I've always wondered is whether the CC could be reprogrammed to be more efficient (get closer to the ideal)? And if so, what would it do, and would it benefit from additional sensors?

The kind of things I have in mind:-

- Allowing it to drift around the target speed (say 67-73 when the target is 70). That would allow it to ease off some of the time, and to sense the load on the engine when easing off/accelerating.

- Adding an inclinometer so that the car could sense the gradient better and ease off sooner when encountering a downhill section.

- Setting a maximum acceleration rate to target speed. (At the moment my CC has a lead foot when the target speed is some way away).

Gloomendoom

Cornucopia wrote: »

I tend to use cruise control on longer distance drives.

My logic is this: the type of cars that I drive give their best MPGs on this type of driving (60-80mpg), and I do not have the patience to drive frugally for hours on end, therefore if the CC is 10% less efficient than the theoretical ideal, it is still better than I could manage myself.

The cruise control on my car always wants to return to the set speed as quickly as possible and will use full throttle and kickdown if necessary. Not good for mpg.