Just found this. True or false?

[dozypillock]

Economical with the truth? Ten myths about mpg figures | Top Gear

My own experience says I never achieve the so called MPG figures, or anywhere near them. 16 mpg is good for me as I enjoy my car. I accept my driving style probably has an influence....but I bought it to enjoy.

Neil

 

[kid-jensen]

Certainly explains why I never get close to the Official figures....I could never drive like that.

 

[tec]

I have never driven for economy, and I treat the manufacturers figures just as a guide to compare different cars when buying, rather than expecting to obtain their MPG figures in real life.

 

[grober]

Economic with the journalism more like -- this sort of stuff has been known for years. Now if they had come up with a comprehensive survey on which manufacturers [ if any] came closest in the real world to their [ largely theoretical] published figures - that might have been worth reading. I believe Honest John did an survey using fuel consumption data submitted from real world owners on this very topic.
Real MPGs | Honest John

 

[MancMike]

If I drive "for economy", I can just about manage the manufacturers figures.

It's 20mpg for around town, 39/40 on the motorway and combined 30, but I never do combined. My commute is 4 miles, 8 miles total and I rarely venture further, but when I do, it's a lot further, so all motorway. I can just about stay above 20 unless there's major congestion in manchester city centre, and can manage high 30s on the motorway.

Honest John's crowd sourced figures confirm too, as it gets 99% which is about the closest I can see for most cars.

C280 29.1 mpg 28.9 mpg 99%

Mercedes-Benz C-Class 2007 - Real MPGs | Honest John

If I get a lot of crawling traffic or if I put my foot down to enjoy the V6 roar, then I get 14/15/16 mpg.

 

[boxbrownie]

Well number 2 is downright incorrect, virtually every manufacturer tests on their own dynos. It is a strictly adhered to test procedure stipulated in EC regs.

This is a "done to death" subject that will never fade away, but makes for good page fillers and interweb fluff.

 

[geraldrobins]

If I drive "for economy", I can just about manage the manufacturers figures.

It's 20mpg for around town, 39/40 on the motorway and combined 30, but I never do combined. My commute is 4 miles, 8 miles total and I rarely venture further, but when I do, it's a lot further, so all motorway. I can just about stay above 20 unless there's major congestion in manchester city centre, and can manage high 30s on the motorway.

Honest John's crowd sourced figures confirm too, as it gets 99% which is about the closest I can see for most cars.

C280 29.1 mpg 28.9 mpg 99%

Mercedes-Benz C-Class 2007 - Real MPGs | Honest John

If I get a lot of crawling traffic or if I put my foot down to enjoy the V6 roar, then I get 14/15/16 mpg.

You say you obtain 39/40 on the motorway but the official figures don't give a motorway comparison anymore, just an extra urban. I achieve around the official combined mpg on the motorway when its fairly warm outside.

 

[geraldrobins]

Presumably the official test figures don't take air resistance into account either or do they?
My wife drive a cmax which is tall and that achieves a much lower percentage of the official figures than mine does which I assume is down to more air flow resistance and susceptibility to wind etc.

 

[MancMike]

official figures don't give a motorway comparison anymore, just an extra urban.

Yeah, extra urban is what I'm classing as motorway miles. Either way I've had 39mpg out of it, which is impressive, although a proper effort.

If I'm doing reasonable speed and "making progress" on the motorway and not fussed about MPG, enjoying the odd lorry flyby, then I'll get low 30s.

 

[Deleted member 6183]

I have seen the official figures on most of my cars.

However, this is true only under certain circumstances which are work and holiday use which will both involve about 85/15 split between motorway and city driving.

It's actually uncanny how I will see the combined figure almost to the decimal place.

Lots of city, brum-brum, driving will hit consumption hard.

 

[C180CGI]

Every car we have had, including this Merc, we have beaten the MPG figures by far. It depends on how you drive the car. To beat the MPG figures, its really easy, however it can only be done on a manual really. Go first gear till 10 MPH, then switch to second gear and drive it to 35 ish MPH then put it into gear 4 and cruise in this gear until you reach 50 mph (we drive city so we normally just sit at 40 MPH in gear 4) and then at 55ish MPH put it into gear 6 and finally use a light foot when accelerating. I guarantee if you drive like this for an hour you will beat the MPG figures. I got 49.9 MPG out of my Merc, 1.8 CGI. The MPG was still increasing however my journey came to an end.

 

[Rory]

Well number 2 is downright incorrect, virtually every manufacturer tests on their own dynos. It is a strictly adhered to test procedure stipulated in EC regs.

This is a "done to death" subject that will never fade away, but makes for good page fillers and interweb fluff.

It's also not true that they press the eco button. The car has to be run in its default condition - hence why cars default to eco mode now.


Also 4 - says they calculate MPG from emissions. This used to be the case, but I'm sure that's changed and they actually measure the fuel used now - hence emissions and MPG aren't exactly in sync anymore.

 

[boxbrownie]

There were a few "discrepancies" in those points, I just highlighted the first most obvious one, it all makes for good column inches though, and makes it seem the motoring journo's know what their talking about

 

[wongl]

The tests are performed when the car has warmed up to normal operating temperature, so if you only do short journeys, your car may never warm up properly and you may fall way short of the test statistics since the engine typically burns more fuel during its warm up cycle.

Not sure if they still do it, but in the past it is common for the ECU to recognize the test cycle (from the starting procedure) and enter into a extra lean/low emission mode to help achieve the most favorable test results.

 

[boxbrownie]

The MPG was still increasing however my journey came to an end.

Was that just after the sanity of every driver queuing up behind you?

 

[SLKNick]

The dyno simulation used for producing these figures is a standardised procedure agreed between the various manufacturers and their trade associations. It's purpose is to provide a meaningful(?) comparison between different vehicles and not as many people imagine, to provide a true indication of what the vehicle will achieve in real use.

The simulation is run on a rolling road with the wheels turning and drivetrain loaded but with the vehicle itself stationary with respect to the air. The simulation does not take into account the effects of aerodynamic drag that we encounter in actual usage when the car has to push the air out of its way. So even if you drove the car on the road exactly in accordance with the simulation you would never achieve the same figures.

 

[boxbrownie]

And here is a portrait of the test driver I took..........I couldn't get him to smile

As said, it follows a strict routine, no fiddling or cheating!

 

[pembssurf]

FFS buy a car like a Merc to drive it. Not to worry about mpg. If your worrying about mpg you should not have bought a premium car.

 

[MancMike]

Sometimes people just want to know they're getting the MPG they're supposed to be, so that;
A: They've not been lied to too spectacularly by the manufacturer.
B: So that they know their engine and drivetrain is in good health.

edit: oh look those two sentences are exactly the same length, fancy that.