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27.5 MPG down to 23.5 MPG Mystery
Miscellaneous UK car topics Other UK car topics (uk.rec.cars.misc)
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#1
 
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27.5 MPG down to 23.5 MPG Mystery -
02-21-2007
, 07:52 AM
#2
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I have a 2004 Volvo S60 in which my typical weeks see me driving the same types of roads with little variation in route and miles. Owned for 18 months and for first 12 months the MPG was averaging 27.5 with me as the only driver. However in the last 6 months the average is down to 23.5 and the only thing that changed was in a two week period six months ago I had four new tyres, a main dealer service and two new rear shock absorbers. Any thoughts on which of the three changes may have reduced my MPG? Ken |
you travel slightly further for each wheel rotation. The car doesn't
know this, and thus fuel economy can *appear* to dip slightly after new
tyres. Should not be more than 1-2% max though - and your fall is more
in the 15% league.
2) Fuel economy can fall during winter, with colder starts, heavier use
of lights, electric rear window etc. Again - not enough to make
anywhere near a 15% drop in economy - unless you always do very short
journeys with the engine always cold or cold-ish.
3) What tyres were put on? If you had some "eco" low-rolling resistance
tyres on before, and now have some which are not, that may account for
some of the difference. Vendors of "eco" tyres often claim up to 10%
improvement in fuel economy - although in my experience 5% max is more
likely in the real world.
4) When did you last check your tyre pressures? Do not assume the
garage got them right - or even if it did, that they are still correct 6
months later! Under-inflated tyres can cause a 10% drop in fuel
economy.
My best guess is a combination of all of these.
Ian
--
Ian Riches
Bedford, UK
#3
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I have a 2004 Volvo S60 in which my typical weeks see me driving the same types of roads with little variation in route and miles. Owned for 18 months and for first 12 months the MPG was averaging 27.5 with me as the only driver. However in the last 6 months the average is down to 23.5 and the only thing that changed was in a two week period six months ago I had four new tyres, a main dealer service and two new rear shock absorbers. Any thoughts on which of the three changes may have reduced my MPG? |
consumption was triggered at that point ? If you have kept detailed
records, it should be clear if it has gently declined or dropped
suddenly.
I've kept records for nearly 4 years, and a smoothed graph (averaged
over 3 fill-ups) shows dips in mpg every winter, but not by the %age
amount you have seen (in my case dropping to an average of about 38-39
from 40-42 in summer). I put this down to increased warm-up times and
the slightly poorer calorific value of fuel in winter. I can't detect
any change in the general trend at service times.
23.5mpg sounds poor by most standards, unless you do a lot of stop-
start driving.
--
"There's no future in time travel"
#4
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On Feb 21, 1:52 pm, "Ken" <Reply to NG only> wrote: I have a 2004 Volvo S60 in which my typical weeks see me driving the same types of roads with little variation in route and miles. Owned for 18 months and for first 12 months the MPG was averaging 27.5 with me as the only driver. However in the last 6 months the average is down to 23.5 and the only thing that changed was in a two week period six months ago I had four new tyres, a main dealer service and two new rear shock absorbers. Any thoughts on which of the three changes may have reduced my MPG? Only the service, really, but how sure are you that the change in fuel consumption was triggered at that point ? If you have kept detailed records, it should be clear if it has gently declined or dropped suddenly. I've kept records for nearly 4 years, and a smoothed graph (averaged over 3 fill-ups) shows dips in mpg every winter, but not by the %age amount you have seen (in my case dropping to an average of about 38-39 from 40-42 in summer). I put this down to increased warm-up times and the slightly poorer calorific value of fuel in winter. I can't detect any change in the general trend at service times. 23.5mpg sounds poor by most standards, unless you do a lot of stop- start driving. -- "There's no future in time travel" |
according to the cars computer. Every month throughout 12 months was in the
region of 27.5 and the months following the three events was 23.5.
Everything about my driving routine is so boringly the same week after week.
My own feeling is the service as the car does not feel quite as it should be
post service so now thinking of getting a smaller garage with old fashioned
mechanic to take a look.
Ken
#5
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In article <45dc4e32$0$28974$da0feed9 (AT) news (DOT) zen.co.uk>, "Ken" <Reply to NG only> says... I have a 2004 Volvo S60 in which my typical weeks see me driving the same types of roads with little variation in route and miles. Owned for 18 months and for first 12 months the MPG was averaging 27.5 with me as the only driver. However in the last 6 months the average is down to 23.5 and the only thing that changed was in a two week period six months ago I had four new tyres, a main dealer service and two new rear shock absorbers. Any thoughts on which of the three changes may have reduced my MPG? Ken 1) New tyres are slightly larger than old tyres (deeper tread!), and so you travel slightly further for each wheel rotation. The car doesn't know this, and thus fuel economy can *appear* to dip slightly after new tyres. Should not be more than 1-2% max though - and your fall is more in the 15% league. 2) Fuel economy can fall during winter, with colder starts, heavier use of lights, electric rear window etc. Again - not enough to make anywhere near a 15% drop in economy - unless you always do very short journeys with the engine always cold or cold-ish. 3) What tyres were put on? If you had some "eco" low-rolling resistance tyres on before, and now have some which are not, that may account for some of the difference. Vendors of "eco" tyres often claim up to 10% improvement in fuel economy - although in my experience 5% max is more likely in the real world. 4) When did you last check your tyre pressures? Do not assume the garage got them right - or even if it did, that they are still correct 6 months later! Under-inflated tyres can cause a 10% drop in fuel economy. My best guess is a combination of all of these. Ian -- Ian Riches Bedford, UK |
Thanks for the reply. Not aware I had special "eco" tyres on but as a I just
said, in other post, now feeling it could be the service. Shame as it was
the main dealer but they proved themselves silly with another issue, at that
time, which they (technician and workshop supervisor) said needed a new
exhaust system £500 part plus. I had my small garage look who said shock
absorbers which they did and problem was solved.
Ken
#6
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"John Laird" <lairdy (AT) gmail (DOT) com> wrote in message news:1172070943.873025.68230 (AT) p10g2000cwp (DOT) googlegroups.com... On Feb 21, 1:52 pm, "Ken" <Reply to NG only> wrote: I have a 2004 Volvo S60 in which my typical weeks see me driving the same types of roads with little variation in route and miles. Owned for 18 months and for first 12 months the MPG was averaging 27.5 with me as the only driver. However in the last 6 months the average is down to 23.5 and the only thing that changed was in a two week period six months ago I had four new tyres, a main dealer service and two new rear shock absorbers. Any thoughts on which of the three changes may have reduced my MPG? Only the service, really, but how sure are you that the change in fuel consumption was triggered at that point ? If you have kept detailed records, it should be clear if it has gently declined or dropped suddenly. I've kept records for nearly 4 years, and a smoothed graph (averaged over 3 fill-ups) shows dips in mpg every winter, but not by the %age amount you have seen (in my case dropping to an average of about 38-39 from 40-42 in summer). I put this down to increased warm-up times and the slightly poorer calorific value of fuel in winter. I can't detect any change in the general trend at service times. 23.5mpg sounds poor by most standards, unless you do a lot of stop- start driving. -- "There's no future in time travel" The only record I have kept is a monthly reading of the average MPG according to the cars computer. Every month throughout 12 months was in the region of 27.5 and the months following the three events was 23.5. Everything about my driving routine is so boringly the same week after week. My own feeling is the service as the car does not feel quite as it should be post service so now thinking of getting a smaller garage with old fashioned mechanic to take a look. Ken Take it back to the garage and tell them to put it right! It might be a |
in each week. Don't forget as prices rise you will get less miles for your
money !
#7
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"Ken" <Reply to NG only> wrote in message news:45dc81fb$0$2444$db0fefd9 (AT) news (DOT) zen.co.uk... "John Laird" <lairdy (AT) gmail (DOT) com> wrote in message news:1172070943.873025.68230 (AT) p10g2000cwp (DOT) googlegroups.com... On Feb 21, 1:52 pm, "Ken" <Reply to NG only> wrote: I have a 2004 Volvo S60 in which my typical weeks see me driving the same types of roads with little variation in route and miles. Owned for 18 months and for first 12 months the MPG was averaging 27.5 with me as the only driver. However in the last 6 months the average is down to 23.5 and the only thing that changed was in a two week period six months ago I had four new tyres, a main dealer service and two new rear shock absorbers. Any thoughts on which of the three changes may have reduced my MPG? Only the service, really, but how sure are you that the change in fuel consumption was triggered at that point ? If you have kept detailed records, it should be clear if it has gently declined or dropped suddenly. I've kept records for nearly 4 years, and a smoothed graph (averaged over 3 fill-ups) shows dips in mpg every winter, but not by the %age amount you have seen (in my case dropping to an average of about 38-39 from 40-42 in summer). I put this down to increased warm-up times and the slightly poorer calorific value of fuel in winter. I can't detect any change in the general trend at service times. 23.5mpg sounds poor by most standards, unless you do a lot of stop- start driving. -- "There's no future in time travel" The only record I have kept is a monthly reading of the average MPG according to the cars computer. Every month throughout 12 months was in the region of 27.5 and the months following the three events was 23.5. Everything about my driving routine is so boringly the same week after week. My own feeling is the service as the car does not feel quite as it should be post service so now thinking of getting a smaller garage with old fashioned mechanic to take a look. Ken Take it back to the garage and tell them to put it right! It might be a fault with the computer as you have not once mentioned putting more petrol in each week. Don't forget as prices rise you will get less miles for your money ! |
they have my money for the service?
#8
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I have a 2004 Volvo S60 in which my typical weeks see me driving the same types of roads with little variation in route and miles. Owned for 18 months and for first 12 months the MPG was averaging 27.5 with me as the only driver. However in the last 6 months the average is down to 23.5 and the only thing that changed was in a two week period six months ago I had four new tyres, a main dealer service and two new rear shock absorbers. Any thoughts on which of the three changes may have reduced my MPG? Ken |
it's likely to be the electronic throttle module (I'm assuming it's a petrol
turbo) especially if it has been driven economically.
--
"Get a paper bag"
#9
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Ken <Reply to NG only> wrote: I have a 2004 Volvo S60 in which my typical weeks see me driving the same types of roads with little variation in route and miles. Owned for 18 months and for first 12 months the MPG was averaging 27.5 with me as the only driver. However in the last 6 months the average is down to 23.5 and the only thing that changed was in a two week period six months ago I had four new tyres, a main dealer service and two new rear shock absorbers. Any thoughts on which of the three changes may have reduced my MPG? Ken Is the idle dead smooth or does it hunt a little? - google for VOLVO ETM - it's likely to be the electronic throttle module (I'm assuming it's a petrol turbo) especially if it has been driven economically. |
It is petrol and I am going to get into our small garage where the owner has
a V70 so is familiar with this type of car.
Ken
#10
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"John Laird" <lai... (AT) gmail (DOT) com> wrote in message The only record I have kept is a monthly reading of the average MPG according to the cars computer. Every month throughout 12 months was in the region of 27.5 and the months following the three events was 23.5. Everything about my driving routine is so boringly the same week after week. My own feeling is the service as the car does not feel quite as it should be post service so now thinking of getting a smaller garage with old fashioned mechanic to take a look. Ken |
matches what the computer says.
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