Official vs Real World Fuel Economy

Right - full 7 days done.

Been on the motorway once for 200 miles, total mileage for the week 430 miles.

Actual = 39.3mpg. Official = 49.6mpg.
 
merlin said:
Right - full 7 days done.

Been on the motorway once for 200 miles, total mileage for the week 430 miles.

Actual = 39.3mpg. Official = 49.6mpg.
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Ouch.

It does seem to be the case now that the manufacturers claimed economy and what you can actually get when driving them every day are massively different.

I'm trying to work out when this change took place and I guess it coincides with the manufacturers playing games to get their car ultra efficient on the test cycles to get good book figure.
 
lordrobs said:
Ouch.

It does seem to be the case now that the manufacturers claimed economy and what you can actually get when driving them every day are massively different.
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An independant body determines the figures against a drive cycle nobody realisticaly does. Manufacturers just report the numbers rather than claiming them. Of course there is now every incentive to massage ECU calibrations ontop of the changes they make to minimise those figures.
 
[TW]Fox;18654157 said:
The numbers are based on a 530i with no warranty versus a 330i with warranty. It is in this area where the savings are largest.
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Just looked at your PH Blog. You're on your 3rd clutch now??

Do you take your car to be repaired at BMW? Just noticed that you had your water pump replaced for £120, which, assuming it was from the dealers, seems very cheap?
 
Jonnycoupe said:
An independant body determines the figures against a drive cycle nobody realisticaly does. Manufacturers just report the numbers rather than claiming them. Of course there is now every incentive to massage ECU calibrations ontop of the changes they make to minimise those figures.
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Sorry, what I wrote wasn't clear. As you say it is the optimisation of the car to get good test figures that I was referring to rather than un substantiated claims from the manufacturer.
 
On the motorway I can pull in the official 58mpg without too much trouble - but that goes straight down the pan on the 30/40mph roads where the car doesn't pull in anywhere near the official.

With the price differential at the nozzle petrol to diesel I'm half thinking there wouldn't be that much additional cost to switch back to petrol - I need to do the sums.
 
merlin said:
On the motorway I can pull in the official 58mpg without too much trouble - but that goes straight down the pan on the 30/40mph roads where the car doesn't pull in anywhere near the official.
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Thats a issue on the heavier cars I guess. Much like the 320 ED that gets a load of good media I imagine that also drops off a fair amount when in that sort of driving.

What sort of speed would 58mpg cruising be?
 
merlin said:
With the price differential at the nozzle petrol to diesel I'm half thinking there wouldn't be that much additional cost to switch back to petrol - I need to do the sums.
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I'm thinking of swapping to a cheap (boring :( ) car for a bit to try and get my dormant savings building up again and I'm having the exact same thought.

At the moment my commute in a years time will either be 10 miles of B-Roads or 60 miles of mainly A-roads. I was thinking that the former = petrol and the latter = diesel but I'm honestly wondering if I should just make the jump to a cheaper petrol now as even with the longer commute I'll still over all come to about the same outcome financially in 2 or 3 years time.
 
Mine has gone up since the warmer weather has started coming in. Gone from 30mpg around town to 35mpg. Much better lol. Not tested this on the motorway yet.
 
530i Auto

Claimed MPG = 26.4 MPG
Previous actual MPG = 24.5 MPG
Actual MPG after I decided to try and improve economy = 27 MPG
Actual MPG on a trip to Plymouth the other day = 33.2 MPG

In conclusion, it depends completely how you drive and where.
 
Just one thought on here. There's a lot of comments of "my fuel consumption meter says...".
Personally I've never come across a completely accurate one. My old BMW was usually optimistic by 2-3mpg, my present Volvo by around 10% and a VW I owned a good while back was an awesome 50% optimistic.

Who's actually sanity checked theirs?
 
Mr_Sukebe said:
Who's actually sanity checked theirs?
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You'll note quite a few people in this thread - there is one just two posts above you - have provided calculated consumption figures to go alongside the fuel computer figures.

I keep a real world running total of mine using an app on my phone - my trip computer is usually about 0.5mpg optimistic.
 
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