Why does computer stop at 40 mpg?????

[mercpaul]

How do we upgrade firmware because mine is the same to only reads 40 tops

 

[markjay]

I am assuming this will require a trip to the dealer, because firmware upgrades generally require genuine STAR with paid subscription etc (and I also found out that Indies are mostly reluctant to carry this out even if they do have the required kit).

 

[Deleted member 65149]

It would perhaps be better to have a gauge which showed by means of a swinging arm when we were driving most economically...after all, that's all the instant read out shows. The real mpg is "since reset".

Like this sort of thing that came as standard on some cars but we could easily fit ourselves I'm sure as far back as the 70s and probably even earlier?

 

[V12]

I am assuming this will require a trip to the dealer, because firmware upgrades generally require genuine STAR with paid subscription etc (and I also found out that Indies are mostly reluctant to carry this out even if they do have the required kit).

Because firmware updates can take many hours sometimes and keep a star machine and car bay tied up for several hours for quite a small charge. (Sometimes free)

 

[markjay]

Like this sort of thing that came as standard on some cars but we could easily fit ourselves I'm sure as far back as the 70s and probably even earlier?

My 1982 Astra indeed had something similar, 'Econometer' as they called it then, essentially a gauge with red, yellow, and green zones, and a vacuum tube connected to the carburettor.

 

[Dieselman]

I asked about firmware upgrade for my car and was told it was on the latest. Still only 40mpg on the display.

 

[geraldrobins]

So nobody why knows then?

My car is quoted at 67 extra urban so it strange not having a guage that can reflect that

I agree but the mpg from start and mpg from reset do.

 

[JethroUK]

I agree but the mpg from start and mpg from reset do.

I was hoping I could see the optimum motoway speed to maximise my mpg but obviously

Frankly I see very few uses for it if it cant do that

 

[V12]

Do you really want to drive that slow?!

Probably find around 50mph is optimum for most MB.

 

[Bobby Dazzler]

I was hoping I could see the optimum motoway speed to maximise my mpg but obviously

Frankly I see very few uses for it if it cant do that

Instantaneous isn't much good for that.

If you want to apply some science to working it out find a stretch of motorway which is fairly flat, set your cruise control at a specific speed (say 50 mph) and then reset you trip computer. Don't accelerate or break for a set distance (say 5 miles) and note the average MPG since reset at that point. Repeat for each speed increment.

To try and add some consistency, do it between two marked points, one shortly after a motorway junction and another marked point before an exit. You can then do two way runs for the same speed. Repeat the circuit for each speed increment.

Generally though, the slowest speed you can cruise at in top gear without the gearbox shifting down (or labouring the engine in a manual) will be close to best consumption. Between 50 and 60 MPH is about right but will vary by car.

 

[Dieselman]

I find modern diesel give the best economy at about 1500 Rpm in top gear.

Which is probably where I'm going wrong.

 

[geraldrobins]

I was hoping I could see the optimum motoway speed to maximise my mpg but obviously

Frankly I see very few uses for it if it cant do that

I doubt it would do that anyway. Ive had VWs that have a instant readout and have one on a ford. It doesn't stay constant for long, if you lift it will go to 200mpg but on a slight level or incline it will drop to much lower. Accelerate even gently and it goes to about 20-30 mpg. You would have to find a perfectly flat road with no breeze at all to keep it constant.

 

[markjay]

I doubt it would do that anyway. Ive had VWs that have a instant readout and have one on a ford. It doesn't stay constant for long, if you lift it will go to 200mpg but on a slight level or incline it will drop to much lower. Accelerate even gently and it goes to about 20-30 mpg. You would have to find a perfectly flat road with no breeze at all to keep it constant.

Some years ago I drove a 1997 Granada Scorpio that had an 'on board computer' - cutting edge technology at the time - and when coasting downhill it was showing the instant consumption as 999.

 

[pkp]

MPG instantaneous display shows 40mpg max

Hello,
I used to drive a Volvo and used to get correct mpg display at each speed which enabled me to find the best speed for optimum MPG.

The April 14 REG E Class Mercedes I just bought, does not show >40mpg. Has any one resolved this by software upgrade?

 

[CowleyStJames]

For the best fuel economy in my S212 E250, driving at 75mph gives me around 50mpg.
That's about 1800rpm

 

[Petrol Pete]

Can I please, please have one of these 40mpg thingy's you lot are going on about.

The one on my C55 AMG must be broken...it never goes higher than 25mpg

Pretty please.