Official/claimed fuel consumption figures vs. real world

[wedge]

Figures based on EU combined numbers and mixed driving conditions in the real world.

Pug 106 1.1 - over 45mpg (claimed) but got about 42 IIRC

Pug 206 1.4 16v - over 45mpg (claimed) but got between 38-40; 42-43 with Shell V power

Audi A4 Avant 1.8T - 34mpg (claimed) but got just under 30; 33 with Shell V Power

Toyota Celica 1.8 (140) - 36.7 mpg (claimed) but doing 33; 35 when drinking Shell V Power

Edit: published figures are done in controlled environments and can be difficult to achieve in the real world

[schmenke]

Fuel consumption varies greatly depending on how the vehicle is driven.

The published consumption on my Hyundai POS, 1.5 liter is 33mpg. I've recently measured it at ~40mpg :) .

[Steve Boyd]

I don't believe the trip computer figure either! Every car I've had with one seems to be about 10% optimistic compared with noting the mileage every time the tank is filled.

[Daniel]

I don't believe the trip computer figure either! Every car I've had with one seems to be about 10% optimistic compared with noting the mileage every time the tank is filled.

I find the trip on our 500 gets more inaccurate the more short journeys the car is used on. When we drove through Europe last summer which was more or less get up in the morning, drive till we have lunch and then drive to the hotel in the evening, it was more or less spot on.

It's done an average of 47.7 mpg (calculated on fill ups, not the trip computer) over the 24,800 miles it's done so far. The combined mpg figure it's meant to achieve is 55mpg and tbh it would achieve this if it wasn't on wider tyres which seem to affect economy by about 10-15%. When it's on summer rubber it probably does about 45mpg and on the narrower winter rubber it seems to do just over 50 and did its best figure of 56.6 :)

Sorry if I sound anal but I record every fuel up on http://www.fuelly.com/driver/306maxi/500

Schmenke, are those figures US MPG or UK MPG?

[donKey jote]

the trip computer calculation in mpg or l/100km depends on 3 factors:

1. absolute fuel consumption (volume) -> calculated by the engine control system and in my experience fairly accurate :)

2. distance -> usually estimated using the wheel rotation and a nominal wheel circunference. Any inaccuracies in this calculation also show up when you compare your speed odometer and eg GPS (assuming you're not driving too sideways or up or down a steep hill :p )

3. a fiddle factor that can be tweeked at your friendly garage if you take your car in and complain the consumption is too high ;) :bandit:

[Daniel]

the trip computer calculation in mpg or l/100km depends on 3 factors:

1. absolute fuel consumption (volume) -> calculated by the engine control system and in my experience fairly accurate :)

2. distance -> usually estimated using the wheel rotation and a nominal wheel circunference. Any inaccuracies in this calculation also show up when you compare your speed odometer and eg GPS (assuming you're not driving too sideways or up or down a steep hill :p )

3. a fiddle factor that can be tweeked at your friendly garage if you take your car in and complain the consumption is too high ;) :bandit:

Well, with the 500 it seems to be that the more journeys you do per tank, the less accurate it is. When I was working and doing ~40 miles a day and filling up every week and a half or so it seemed to be about 10% out but when we were driving in long stints on the continent it was more or less 100% accurate.

I wouldn't like to speculate why though, probably crappy Italian designed and Polish built electrics :p

[schmenke]

I ...Schmenke, are those figures US MPG or UK MPG?

Good question. I'm not sure. I calculated that from 5.7 liters/100kms (measured). I'll let someone else confirm the math(s) :p :

[Daniel]

Good question. I'm not sure. I calculated that from 5.7 liters/100kms (measured). I'll let someone else confirm the math(s) :p :

That's US mpg (41) which is nearly 50 UK mpg which is pretty darn good :)

[Sonic]

Well as my car gets driven by L platers all day at 25mph it's MPG is poor - 32MPG. However on the odd occasion I get to drive it myself for a full tanks worth of motoring I can better the claimed figure.

On the other hand no matter how careful I am in the wife's Seat its just pish poor - 28MPG at best. Mostly due to terrible gearing - 3,600RPM at 70mph. And that's a lesson to test drive on all road types I will never forget.

[schmenke]

That's US mpg (41) which is nearly 50 UK mpg which is pretty darn good :)

Yeah, it's surprised me too TBH. Maybe my trip odometer is off (or the meters on the petrol pumps... :p : )

[Daniel]

Well as my car gets driven by L platers all day at 25mph it's MPG is poor - 32MPG. However on the odd occasion I get to drive it myself for a full tanks worth of motoring I can better the claimed figure.

The 500 has similar issues with economy, her name is Caroline and she likes to brake :p . Seriously don't understand the point of accelerating and then seconds later to be braking :mark:

[schmenke]

^

Similar here with Mrs. schmenke... a lead-foot on both pedals :p : .

And I can't seem to convince her to take the POS instead of the swagger-wagon, which consumes twice the gas, when she pops out to the local convenience store for a jug of milk. Or better yet, take a bicycle, but I don't dare mention that to her... :uhoh:

[airshifter]

I'm not sure about other countries, but here in the US the recently revised the rating system for the EPA fuel estimates on the window stickers. It includes quicker acceleration, use of AC, higher tops speeds, etc and is supposed to be close to the average "real world" driving conditions.

The good thing is that people that driver slower almost always beat the MPG figures.

We have two fuel pigs and one smaller car that gets decent MPG.

[donKey jote]

Or better yet, take a bicycle, but I don't dare mention that to her... :uhoh:
to be honest, I don't see how putting a bicycle in the trunk will help fuel consumption either... :erm: :arrows: :dozey:

[bluegem280]

Fuel consumption varies greatly depending on how the vehicle is driven.

The published consumption on my Hyundai POS, 1.5 liter is 33mpg. I've recently measured it at ~40mpg :) .

Great, smooth driving, mostly I find people measured real mpg less than official claim. Is it driven on stock tires? if it ran tires on smaller diameter than standard it may rotate faster than it should. The odo may show wrong read. :)

Besides all reasoning mentioned above, the correct and shortest routing to cover the same destination is important. Driving needs navigator, someone accompany you driving. :)

[555-04Q2]

I have never been able to get even remotely close to the claimed consumption figures of the manufacturers, no matter how carefully I drive.

[Mark in Oshawa]

^

Similar here with Mrs. schmenke... a lead-foot on both pedals :p : .

And I can't seem to convince her to take the POS instead of the swagger-wagon, which consumes twice the gas, when she pops out to the local convenience store for a jug of milk. Or better yet, take a bicycle, but I don't dare mention that to her... :uhoh:

First off, Schmenke, you quote 5.7 liters to the gallon? That is not the right number. I believe Imperial or British gallons are 4.19 Liters, and the US Gallon is 3.9 Liters. so you were I think neither.

I only know this from messing about trying to figure out fuel mileage in the big rig and matching it to the computer read out on the dash. A man does get bored on the road, which of course is why I had to give it up! (BTW, a fully loaded 2008 Frieightliner Century with a 10 speed and 465hp Detroit topped out for me on one trip from Cheyenne Wyoming to Gary Indiana at 9.1mpg with 44000lbs worth of freight. This was mainly downhill...lol...as Cheyenne is a Mile above sea level and Gary is 512 a.s.l)

I find the advertised fuel mileage is just a rough guide to compare cars to compare. Most of my experience is shown by what Daniel has pointed out, you rarely get that good mileage unless you work at it.

AS for your wife Schmenke, I feel your pain brother. My wife has a lead foot too....but we own nothing but 4 cylinders so I have tamed that out of her. Now getting me to slow down hasn't always been easy, but with Gas over a $1.30 a liter now, I am getting more light on the gas all the time!

[Mark]

It's 4.54 and 3.78

[Daniel]

I find the advertised fuel mileage is just a rough guide to compare cars to compare. Most of my experience is shown by what Daniel has pointed out, you rarely get that good mileage unless you work at it.

I think REALLY good results hangs on whether you really try. There seem to be a lot of people with 500's who are getting high 30's or low 40's which is just amazingly poor!

These two guys have exactly the same car and same tyres so should be doing more or less the same mpg, yet one guy is doing 56.8 and the other guy 37. To do 37 I'd have to accelerate hard, tailgate people do I have to brake and so on :mark:

http://www.fuelly.com/driver/jrkitching/500
http://www.fuelly.com/driver/blitz7287/500

[Mark]

Entirely depends on the roads they regularly drive on of course. IME if you can cruise at about 55mph then milage is amazing, otherwise not so much :p

[Daniel]

Entirely depends on the roads they regularly drive on of course. IME if you can cruise at about 55mph then milage is amazing, otherwise not so much :p

So true. One of the reasons I'm getting better fuel economy lately is starting a new job which is 9-5 whereas my last job was flexitime. So now if I get to work early there's no advantage and I leave early just to make sure I'm not late. I think my max speed is about 60 or perhaps 65 if I'm overtaking, otherwise I just cruise along at 55. Being dual carriageway most of the way I don't have to speed up to stop some idiot overtaking me over a blind crest or showering me with crap and I don't have to pull out to overtake other people or more commonly, TRACTORS!!!!!!

[MrJan]

So true. One of the reasons I'm getting better fuel economy lately is starting a new job which is 9-5 whereas my last job was flexitime. So now if I get to work early there's no advantage and I leave early just to make sure I'm not late. I think my max speed is about 60 or perhaps 65 if I'm overtaking, otherwise I just cruise along at 55. Being dual carriageway most of the way I don't have to speed up to stop some idiot overtaking me over a blind crest or showering me with crap and I don't have to pull out to overtake other people or more commonly, TRACTORS!!!!!!

I can't do that, I get bored and tune out and don't pay attention like I should. I also always leave late so need to make up time on the 7 mile motorway stretch that I do :erm: Another thing that's annoying is that I've developed a habit of double declutching. I started doing it because I would practice for when I drove the old man's Austin 7, but now the 7 is long gone and I'm still blipping the throttle. Not only does this probably do nasty things to my economy but I wear out the side of my shoes from where I heal/toe it :S

[Daniel]

I can't do that, I get bored and tune out and don't pay attention like I should. I also always leave late so need to make up time on the 7 mile motorway stretch that I do :erm: Another thing that's annoying is that I've developed a habit of double declutching. I started doing it because I would practice for when I drove the old man's Austin 7, but now the 7 is long gone and I'm still blipping the throttle. Not only does this probably do nasty things to my economy but I wear out the side of my shoes from where I heal/toe it :S

It's your money ;) Personally I'd rather go for a thrash on some empty roads rather than the motorway :)

[MrJan]

It's your money ;) Personally I'd rather go for a thrash on some empty roads rather than the motorway :)

It's a few pence a day and allows me 5 minutes more in bed, it's totally worth it :D

My gran once told me how her and my grandad were driving up to Bristol and he was doing 56mph because it's more economical, after a while she said "oh sod it, do a proper speed and I'll pay you the extra". I'm exactly the same, I just want to get to where I'm going, and if it costs a few quid more then so be it.

[Daniel]

It's a few pence a day and allows me 5 minutes more in bed, it's totally worth it :D

It wouldn't be pence though :) I would say most people could cut their fuel bills by at least 10% or so and maybe more depending on the car.

[MrJan]

It wouldn't be pence though :) I would say most people could cut their fuel bills by at least 10% or so and maybe more depending on the car.

Say 30mpg at the minute and 1.35 a litre = £6.13 a gallon, so 20p a mile, 7 miles mean that bit of motorway costs £1.40.....I think. Anyway, say that I could get an extra 15mpg by driving like a granny would make 0.14p per mile, so only 42p for the motorway stretch. That's less than 9p a minute in bed, thoroughly worth it :D

[Daniel]

I'd gladly pay 9p for a minute of sleep :D

[Firstgear]

I think REALLY good results hangs on whether you really try. There seem to be a lot of people with 500's who are getting high 30's or low 40's which is just amazingly poor!

These two guys have exactly the same car and same tyres so should be doing more or less the same mpg, yet one guy is doing 56.8 and the other guy 37. To do 37 I'd have to accelerate hard, tailgate people do I have to brake and so on :mark:

http://www.fuelly.com/driver/jrkitching/500
http://www.fuelly.com/driver/blitz7287/500

Probably, one of these guys is driving mostly in the city, and the other mostly highway.

[airshifter]

Say 30mpg at the minute and 1.35 a litre = £6.13 a gallon, so 20p a mile, 7 miles mean that bit of motorway costs £1.40.....I think. Anyway, say that I could get an extra 15mpg by driving like a granny would make 0.14p per mile, so only 42p for the motorway stretch. That's less than 9p a minute in bed, thoroughly worth it :D

The flaw in this is that you are actually convinced that you are somehow saving 5 minutes on 7 miles worth of driving. Even if the speed limit was 60 and you drove 120, you would only save 3.5 minutes. Not to mention that at those speeds your MPG would be complete crap, so the math figures would probably have a larger delta as well.

Unless you drive on empty roads, just dealing with traffic limits people to probably within 20 mph of the speed limit on the average of a trip. You're hardly saving any time at all in reality.

Not to mention the additional cost of the occasional ticket that you can roll into the fuel costs, and the amount of wasted time dealing with the ticket. ;)

[MrJan]

Not to mention the additional cost of the occasional ticket that you can roll into the fuel costs, and the amount of wasted time dealing with the ticket. ;)

Never got a ticket for speeding, nor has my old man or my brother. And the time isn't saved by the speed, it's mostly saved by how you hit the traffic lights at the end of the motorway ;) Get them in the wrong sequence and you're screwed, I can be there 2 minutes later than usual and it'll cost me at least 5 by the time I get to work.

I'm also not convinced at all, I just always leave home late and hate driving like an old woman :D Like I said before, I find it easier to tune out when I'm on a motorway at those speeds.

(incidentally, the speed limit is 70, Daniel was suggesting driving at 55, while I'd be happier around 75-80, which is generally the sort of cruising speeds that people stick to on a UK motorway)

[Daniel]

Filled up today and the trip computer was saying 55.3 mpg and the real consumption is 53.3, pretty happy with that. Don't think I could honestly do much better.