Dm Has A Dig At Green Cars Not Meeting Claimed Mpg Figures (Prius Incl

[johalareewi]

A Volkswagen Golf 1.6 TDI 105 Bluemotion – VW’s 'eco' badge – has an official fuel economy rating of 74.3mpg yet achieved only 51.8mpg in the What Car? test – a difference of 22.5mpg.

And Toyota’s Prius 1.8 VVT-i T Spirit (built before the recent facelift) scored 70.6mpg in the official tests, but dropped to 52.2mpg in the What Car? results – a difference of 18.4mpg.

http://www.dailymail...on-figures.html

[ph47mf]

well they're just saying what all always know - it's almost impossible to reach the official MPG figure. I'm stuck on about 50MPG, prob about 10MPG out.

[Grumpy Cabbie]

I'll say I can almost guarantee to get the manufacturers figures. Just sit on a flat road at 50 mpg and cruise along and you'll get 80 mph +.

OK, that's not exactly balanced in that the official figures include town use and cold starts, but even then I'm sure you can get pretty near.

Just make sure you have the low rolling resistance tyres at the correct specified pressures and use the correct 0w20 oil if you have an Auris hsd or gen3 Prius and you should be there.

But then again it's the Daily Mail so the journo will hate anything like a hybrid cos it's not an Audi 4 wheel drive all road and thus he'll drive like a twit. If it wasn't for the heavy depreciation and the less than reliable power steering system oh and the higher than it should be new price, then the Prius is a good car.

ph47, are you running llr tyres and if so, at the correct psi's? It makes a BIG difference.

[ph47mf]

yea 42psi at the front and 40 at the back. and the tyres are oem bridgestones i think, well they havent been changed yet as far as i have been told by the dealer.

[timberwolf]

Another news article that is actually just an excuse for an advert for a certain motoring magazine. As one of the comments posted there is already a free web site where people can go to see real world figures.

[Jamesbelfast]

Whilst the link may not be representive it does highlight motorists concerns.

Let's compare it to any other product that claims to save fuel and energy. For instance if you went out and bought a fridge costing £150 the manufacturer claims has an A rating and it was discovered when in use it didn't perform as claimed and was closer to a D rating. it's most likely you could complain and get some backing from a consumer group and even get some or all of your money back. Similar complaints regarding internet speeds have also occured and the ISP's have been forced to amend their advertising claims.

What irks me is simply this. If I go out and buy a £20,000 car I don't have the same rights. For many years motorists have been fobbed off by car manufacturers . Come on folks it's about time us vehicle owners told car manufacturers to be fair and honest when advertising the fuel performance of the products they sell.

[timberwolf]

The evidence of the way many motorist drive would suggest that they are not overly concerned about fuel economy - heavy accelerating and braking, high speeds on motorways and duel carriage ways, lack of anticipation, etc.

For example, if most motorist genuinely wanted to save fuel, everyone would drive at no more than 50 mph on the motorways, I see little chance of that happening.

ISTR that the 1.8l Prius design was influenced by consumer demand from North American and Europe for better performance at motorway and highway speeds, this was at the expense of lower speed fuel efficiency. Personally, I think Toyota should have stuck to the speed limitations of the Gen 2, just think how much more fuel efficient they could have made the Gen 3. But I am also sure the Gen 3 would have been less popular.

[Grumpy Cabbie]

Some motorists manage the manufacturers figures but you have to drive carefully. The fridge analogy isn't quite accurate as the standard test to work out its consumption would be a set number of factors, probably including opening the door an average number of times. Now if you open the fridge more than average or more than the test, then your fridge won't use 230kwh pa but 340kwh for example.

So in my eyes it's exactly the same as the ratings for a car. Drive the car carefully and you get manufacturers mpg's. Open the fridge 12 times a day and use the same electricity that gained the fridge an A rating. Drive the car quickly and you get less mpg's than the rating, open the fridge door 25 times a day, or worse, leave the fridge door open for minutes at a time like my g/f does and the fridge will use more than an A rated fridge. But my more regular usage pattern doesn't mean an A rated fridge should be rerated D, it's just my use is different to the test. The same applies to cars.

Or am I missing something here? They have to set standardised tests and peoples usage patterns vary. Simples :)

[timberwolf]

They are not manufacturers tests or claims. The are lab test and there purpose is to allow the car buyer to independent of any manufacturer's claims, compare the relative fuel efficiency of different cars. They are not something that can usually be achieved in practice because we don't drive around in a lab under the strict conditions used to perform the test - it is completely artificial.

One of the problems with a limited set of tests, is that I guess the manufacturers can cheat, to ensure that their vehicles are designed to pass the specific tests very well, I don't know how likely that is? Or that the tests don't fit very well with advances in the car technology such as hybrids or engine stop/start?

Sadly, I think most of publics' concern of fuel efficiency is about misunderstanding of the official mpg. I believe the concern that motorist has has very little to do with fuel efficiency and everything to do with how much the fuel costs - and the blame should be directed at how much tax there is on petrol and diesel and how the oil is priced (i.e. the market and speculators).

[wass]

I have found that my 38 mile commute to work on single carriageway roads upon which it is very dificult to overtake is extremely boring. As a result, my attention is turned away from attempting to break the land speed record and focused upon driving my car as economically as possible. Maintaining very smooth driving style, carrying corner speed, predicting the road and other road users to further smooth the use of fuel. I am able to get close to or exceed the manufacturers figures for most vehicles which I drive. The most dificult cars to match the laimed fuel consumption figures have been the Prius and the Lexus CT200 whilst I found that it was relatively easy to beat the manufacturers figures for my Honda CRV petrol auto and my Volvo S60 diesel auto.

In all cases, I found that the journey up the A1 from Cambridgeshire to North Notts to see my dad saw the fuel consumption fall dramatically as the average speed rose. My average speed on my daily commute is fairly constant 37 or 38 mph from one day to the next whilst my average speed on my 100 mile jaunt along the A1 is around 63 mph. I also found that the irst 3 or 4 miles of any journey can use a tremendous amount of fuel which is used o warm up the moving parts of the engine and keep the insides of the car nice and comfortable.I am therefore a bit confused as to how the government tests are conducted with a cold engine Maybe they give the manufacturers a head start by conducting all of the tests in a simulated ambient temperature which is significantly higher than the UK average ambient temperature?

[RelaxedDrive]

If they use a rolling road how do they factor in air resistance? Do they change the resistance of the rollers to compensate?

What SOC do they use for Hybrids at the start of the test? Is this done consistantly for all cars?

So far my worst fill-up(calculated) with the Gen 2 has resulted in 45mpg, and the best 58mpg. The worst was during winter and with mostly short (7 mile) journeys to/from work; it's a lot better than my previous car though(usually 33mpg)! :-)

[Grumpy Cabbie]

I also found that the irst 3 or 4 miles of any journey can use a tremendous amount of fuel which is used o warm up the moving parts of the engine and keep the insides of the car nice and comfortable.I am therefore a bit confused as to how the government tests are conducted with a cold engine Maybe they give the manufacturers a head start by conducting all of the tests in a simulated ambient temperature which is significantly higher than the UK average ambient temperature?

My understanding is that the tests are performed on a rolling road with the car under computer control. The temperature is something like 25c with heater and a/c off. They then factor in a calculation for wind resistance.

The American test procedure is more real world in that heating and a/c are used and acceleration times are more realistic. Saying that the US Prius gets an official 50 mpg US which works out about 60 mpg UK (their gallons are smaller), so it's still not bad. If we used their figures, then 60 mpg is easily achievable.

On this topic, I remember an ex colleauge who got a Passat Greenline and he hated it. It has (or had) something like 105 bhp and whilst getting 60 mpg on the flat, it was impossible it most situations and had to be thrashed everywhere to get it to keep up with traffic - which resulted in poorer mpg's than a 'normal' car.

[timberwolf]

<snip>

I am able to get close to or exceed the manufacturers figures for most vehicles which I drive. The most dificult cars to match the laimed fuel consumption figures have been the Prius and the Lexus CT200 whilst I found that it was relatively easy to beat the manufacturers figures for my Honda CRV petrol auto and my Volvo S60 diesel auto.

<snip>

They official mpg are not the manufacturers claims, the official mpg figures are the result of laws/directives.

Do you believe that inflation, measured by various government methods (RPI, CPI, etc) reflects the inflation that you actually experience personally?

The Honda CRV and Volvo Diesel ran inefficiently all year round, in summer they still ran the engine and generated vast amounts of waste heat as a by product, (edit: for example!!), that wasn't needed to heat the passenger compartment. The inefficiency of running the engine all the time, also swamps short journeys, and it was equally inefficient for a range of speeds.

Now the car manufacturers have introduced new technologies to increase the mpg, in the main this appears to have been done by finding ways to turn off the inefficient engines for short periods of time. This change in operating the engine has exposed just how much fuel is wasted by running an engine continuously (in a car at least).

Most drivers, in any make of car, do not get the government's official mpg. Is the official mpg, still good enough to allow the consumer to make a choice of which car to buy? For example, my Prius Gen 2 still gets better mpg than my previous Honda Civic (Auto).

Remember the official mpg figures come from government, do you really want vast sums of tax payers money (and probably higher car prices) to change the tests to make them reflect what the average driver can achieve?

[speedymurr]

Forget mpg, we should measure on efficiency of fuel used compared with power output.

Generally that in practice would be how electrical equipment such as a fridge is measured. Not power (fuel) usage but efficiency of using the "fuel", whether electricity, petrol or diesel.

We might even find some medium sized car engines are more efficient than some smaller models.

[wass]

" They official mpg are not the manufacturers claims, the official mpg figures are the result of laws/directives. Do you believe that inflation, measured by various government methods (RPI, CPI, etc) reflects the inflation that you actually experience personally?"

I seem to have touched a nerve there Timberwolf!

Yes I do believe the figures which the government and manufacturers spout out. Invariably the figures are produced under favourably defined parameters which are deliberately derived in order to illustrate whatever the publisher wishes to convey and this is how I view them, consequently , when I get close to or improve on anyones published mpg figures ,I consider that I have done well. Also when the government tells me that inflation is 3% I understand that in terms of the effect on my pocket I will have done well to see my standard of living drop by only 5%.

Talking of efficiencies, I have worked on quite a number of diferent modes of propulsion including linear motors and most of them including electrical motors are relatively inefficient since in addition to producing motion , they also produce waste heat. (electrical motors , of course, produce a lot of waste heat at the power stations which is the whole reasoning behind wind and wave derived power - harvested indirectly from the waste radiation effects from the sun)

[timberwolf]

Nothing personal, I guess the subject has jangled my nerves more than usual, either that or I'm just extra gloomy because it wont STOP raining!!!

A "waste" radiation from the sun but essential for life on earth

[johalareewi]

As GC mentioned, the USA have EPA figures which are a lot more real life than the UK ones and yes, the article did come over as not just a bash at eco cars but also a plug for a certain magazine.

The interesting thing about UK mpg figures is that with a hybrid, it is possible to get close (or exceed) these figures with normal use. As born out by fuelly data. There are a few prius cars averaging over 70mpg.

[kithmo]

What's going to happen when these Hybrid hating petrol heads force this "real world" economy on us is that the Prius will be found to have CO2 emmisions higher than originally quoted and the VED will increase.

[johalareewi]

As more and more cars get into band A, at some point the VED emission limits will either be abolished or reduced. Can't have the government losing revenue.

[Seamaster73]

The only figures worth a damn are a year's worth of your own calculated on Fuelly — the driver is an important a factor as the car. More so, some might argue.

[wass]

Getting back to the original post, I believe that a news paper commented upon something to do with cars. I was always taught that the only information in a news paper which could be regarded as accurate is the date on the front page, nearly everything else tends to be an approximation. However, I was wrong in thinking that the date is all that can be relied upon, I now have the impression from the Leveson enquiry that dishonesty of news papers may be relied upon too.

:D I will drive my car and make up my own mind regarding its performance.

[Grumpy Cabbie]

Has anyone else here reduced or stopped their purchase of newspapers since the hacking scandal started?

I have. Not just as a protest but really because I find the whole thing distasteful and don't really need a newspaper.

[GreenJuice]

I remember making a conscious decision never to buy a tabloid newspaper again. It was a couple of decades ago after The Sun ran a series of articles about Elton John being !Removed!. I had no personal interest/agenda on the subject, but had a moment of 'awakening' to realise that these and other similar expose's had a pattern. They were not 'news', not in the public interest, aimed in influencing public opinion by editors/journalists who probably weren't leading / role-making members of our society but had a lot of power to have their opinions heard through the use of this media.

I've never bought a Murdoch paper since. I admit reading them occasionally, but will only give my money to sources that earn it from good journalism.

[timberwolf]

Has anyone else here reduced or stopped their purchase of newspapers since the hacking scandal started?

I have. Not just as a protest but really because I find the whole thing distasteful and don't really need a newspaper.

Nope. The only thing that I found note worthy about the hacking scandal was that all of those rich/famous/powerful people couldn't work out how to set a 4 digit pin on their voice mail!

[Lorna2]

I've stopped buying those newspapers as they have a lot of non-news/exaggerated stories. Now I just stick to the local newspaper.