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Discussion Starter · #1 ·
Just been on little trip to new forest over bank holiday , MPG was so good with out really trying too much ,loads of traffic but steady 60/70 and a very quick blast at high speed and still got 76mpg and was still climbing ,very impressed for a car with so much power too :D
 

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Discussion Starter · #3 ·
I will work it out properly when I can , fuel gauge was just touching 3/4 full after 200 miles and after suffering low 30s in my previous 64 plate 1.8 Zaf 5 speed that's fine by me ,so glad I got shot of that car now ,thanks for input though .
 

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Wow! That's amazing! I've been browsing this forum for the past few weeks and been finding outs bits and pieces about the Astra K (particularly the 136 diesel) and am astonished that you achieved 76mpg so easily!
 

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I have the 110 diesel and keep a fuel diary, partly for work, partly because I'm a nerd! Over the first 5200 miles the trip claims 66.9, calculated is actually 57.7, 15.9% over estimating. It really annoys me how over optimistic the trip is, I'm happy with the actual mpg, but the trip over reading means I'm disappointed every time I work out the past tanks mpg. My previous 1series was accurate to well within 5% so it's not impossible to do.

Actual fuel economy does appear to be improving tank by tank though, my urgent tank has taken me 597 miles with an indicated 89 remaining, I've previously not got beyond 580 before losing my nerve with 30 remaining.

I'll be looking out for 'real world' mpg data when it's realeased!
 

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1.6 CDTi 136 getting 83.3mpg.

Oh, and they don't over read anything like as much as said. The car is displaying real time averages. For example, you could be traveling at 60mph, down a slope. So the car is traveling along and not using any fuel. The on board computer calculates all of these off throttle motions and displays the result. Your own calculations will not account for motion with out fuel usage. Hence it will all ways come out much lower.
 

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Ace123 said:
1.6 CDTi 136 getting 83.3mpg.

Oh, and they don't over read anything like as much as said. The car is displaying real time averages. For example, you could be traveling at 60mph, down a slope. So the car is traveling along and not using any fuel. The on board computer calculates all of these off throttle motions and displays the result. Your own calculations will not account for motion with out fuel usage. Hence it will all ways come out much lower.
Nonsense. In your example of travelling down the slope using no fuel, the odometer still logs the distance travelled and no fuel is used, so my brim to brim tank calculation accounts for this distance and for the lack of fuel used in doing so. I fill my tank to brimming and zero the odometer. I then travel 600 odd miles and refill the tank to brimming. The distance travelled divided by the amount of fuel I put in gives accurate mpg, including all the mileage accumulated whilst using no fuel.

I'm really not trying to piss on your chips, claimed 83mpg is still very impressive, it just really annoys me how inaccurate the OBC fuel economy is.
 

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Everybody seems to be forgetting that if at any point their car is not moving, but the engine is still running (i.e. stop / start hasn't kicked in), then you are using fuel without doing any miles. It should also be noted that even if the stop / start is working there will always be a short period when the engine is running and the car isn't moving.

A good example of this is when I arrive home and pull up outside my garage. The engine stops, but as soon as I open the drivers door it restarts and continues to run whilst I open up the garage and take things out of the back of the car. I also have to manouevre the car a bit to get the car into the garage. Whilst this does not use up much fuel each time, i do this daily and sometimes a couple of times a day so it adds up.

Whilst the OBC may be inaccurate, any manual calculation of MPG is equally flawed as i doubt anyone works out how far they move the car in reverse, or how much fuel they are using whilst not moving at all.
 

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Btw i was quite surprise why does it restart the engine whenever i open the door. It's not like the door needs energy to open and its not a "reminder" that the car is still on, most of the manufacturers have beeping sounds for that. So why does Astra start the engine then?
 

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Kristis said:
Btw i was quite surprise why does it restart the engine whenever i open the door. It's not like the door needs energy to open and its not a "reminder" that the car is still on, most of the manufacturers have beeping sounds for that. So why does Astra start the engine then?
Hi

I was told by the salesman it's a safety feature.

Cheers

Paul
 

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MarcR said:
Whilst the OBC may be inaccurate, any manual calculation of MPG is equally flawed as i doubt anyone works out how far they move the car in reverse, or how much fuel they are using whilst not moving at all.
That's not true, manual calculation is far more accurate than the OBC. Manually calculating how far you've travelled on a tank divided by the amount of fuel added is real data, the OBC clearly runs all kinds of algorithms to achieve its (over optimistic) figures.

Also, I'd be very surprised if your reversing adds up to more than a few hundred yards per tank, and any amount of fuel used whilst stationary will impact on both manual and OBC mpg figures.
 

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Giant said:
MarcR said:
Whilst the OBC may be inaccurate, any manual calculation of MPG is equally flawed as i doubt anyone works out how far they move the car in reverse, or how much fuel they are using whilst not moving at all.
That's not true, manual calculation is far more accurate than the OBC. Manually calculating how far you've travelled on a tank divided by the amount of fuel added is real data, the OBC clearly runs all kinds of algorithms to achieve its (over optimistic) figures.

Also, I'd be very surprised if your reversing adds up to more than a few hundred yards per tank, and any amount of fuel used whilst stationary will impact on both manual and OBC mpg figures.
I am not saying that the obc is accurate. But I am saying that working it out manually is also flawed. If you are sitting in traffic for any period of time with the engine running a manual calculation will not take this into account and will therefore return you a lower mpg figure.
 

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MarcR said:
Giant said:
MarcR said:
Whilst the OBC may be inaccurate, any manual calculation of MPG is equally flawed as i doubt anyone works out how far they move the car in reverse, or how much fuel they are using whilst not moving at all.
That's not true, manual calculation is far more accurate than the OBC. Manually calculating how far you've travelled on a tank divided by the amount of fuel added is real data, the OBC clearly runs all kinds of algorithms to achieve its (over optimistic) figures.

Also, I'd be very surprised if your reversing adds up to more than a few hundred yards per tank, and any amount of fuel used whilst stationary will impact on both manual and OBC mpg figures.
I am not saying that the obc is accurate. But I am saying that working it out manually is also flawed. If you are sitting in traffic for any period of time with the engine running a manual calculation will not take this into account and will therefore return you a lower mpg figure.
But even the official test for consumption includes periods where the car is stationary with the engine running. Obviously if you have one journey when you are sat in traffic more than normal that will impact on the figures for the tank, but overall the method used to work out the economy is going to be fairly accurate for each individual driver.
 

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MarcR said:
Giant said:
MarcR said:
Whilst the OBC may be inaccurate, any manual calculation of MPG is equally flawed as i doubt anyone works out how far they move the car in reverse, or how much fuel they are using whilst not moving at all.
That's not true, manual calculation is far more accurate than the OBC. Manually calculating how far you've travelled on a tank divided by the amount of fuel added is real data, the OBC clearly runs all kinds of algorithms to achieve its (over optimistic) figures.

Also, I'd be very surprised if your reversing adds up to more than a few hundred yards per tank, and any amount of fuel used whilst stationary will impact on both manual and OBC mpg figures.
I am not saying that the obc is accurate. But I am saying that working it out manually is also flawed. If you are sitting in traffic for any period of time with the engine running a manual calculation will not take this into account and will therefore return you a lower mpg figure.
Wrong. sure the manual calculation is correct. Standing still = fuel consumption = no mileage. The fuel consumption is equal to what you refill next time and therefore includes "waste" when standing still with the engine running.
 
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