Honest John and Hybrids

[GeeJayW]

The biggest influence on fuel economy in a given car is the driver's right foot. During a test this is taken care of by using highly skilled test technicians that comply with a predetermined speed-time profile which includes rates of acceleration, deceleration and gear change points. Outside of the test lab, drivers are typically much 'heavier' on the controls and as a result use more fuel.

At one time fuel economy figures were often published for 56mph (90 km/h) and 75mph (120 km/h), I can't find a reference to the test method.

 

[gIzzE]

Yeah, it made far more sense.

I don't care what the MPG is when doing an average of 33mpg or whatever the test is, as I don't drive around at 33mph.
I want to know at 80mph (130KMPH fro Europe of course) as it means far more to me.

I always look at the US figures and use them, far better test. Obviously convert back to UK MPG.
But if we used those figures I reckon we would buy far more petrol cars.

The W212 E350 vs E350cdi was a great example, one of the few examples to as not many diesels there, but when see their official MPG figures it is easy to see why.

The US said the 350 was 26mpg city and the 350cdi was 29mpg, then it was 36mpg Highway for the 350 and 41mpg for the 350.

In the UK it said 27mpg urban for the 350 and 42mpg for the 350cdi, then 36mpg extra urban vs 62mpg for the diesel. No wonder so many in the UK buy the diesel with daft figures that like. No wonder so many then get annoyed they feel Mercedes is lying to them.
They are not lying, but the test just doesn't represent the real world, it doesn't even let you compare cars, unless you drive everywhere at 33mph.

 

[grober]

Historically HYBRID technology was adopted by the major car manufacturing nations of the Far East and the USA in response to the 1997 Kyoto Protocol to reduce atmospheric CO2 emissions. European governments on the other hand decided to adopt the DIESEL engine to achieve the same end , probably as a result of heavy Euro car manufacturer and domestic political lobbying. In both cases I believe the manufacturers were happy to sell an imperfectly developed new technology to government and once publicly committed to a particular approach neither of the parties involved were likely to own up to any of its shortcomings. This convenient atmosphere of complacency is only now being addressed as the flaws and economies with the truth of all the parties involved have become more apparent to the public.

 

[GeeJayW]

Part of the issue is making use of the oil barrel. Petrol and diesel come from different parts of the barrel. Converting diesel into petrol or vice versa requires additional plant and more energy use at the refinery. Society is hugely invested in Diesel engine technologies, not just cars, but trucks, buses, vans, ships, trains. Additionally, jet aircraft essentially burn diesel (not exactly the same, but similar hydrocarbons).

Modern diesels are much cleaner than they were and another part of the issue is how the emissions results are reported, not just how they are measured.

Another issue is traffic congestion. When the congestion charges were introduced in London, the lack of HEVs and EVs meant that the traffic numbers dropped. As more and more HEVs and EVs have become available and people/firms have got used to the charges, the traffic numbers have increased, congestion getting worse. About half of the cars in the U.K. are now diesel. Focusing on (the potential harm caused by) NOx emissions means that may result in a ban on (some) diesel vehicles in urban areas. This is a simple tool for reducing urban traffic numbers, which isn't then easily undermined in the short-term.

The next thing to happen will be that all human-driven vehicles will be banned from cities in favour of autonomous HEVs and EVs. Again, much less of those around, so less congestion.

 

[Stratman]

The steady cruising speed (56mph) test of yesteryear was not immune from fiddling either. Road tests frequently complained of a big flat spot between fifty and sixty mph.

 

[David404]

In the real world few cars if any can achieve the fuel economy figures claimed by manufacturers.

And everybody has known for years that both the economy and emissions test were completely useless and came nowhere near to real world results but the state continued to mandate the tests. Now they have finally decided to introduce more representative tests its all the fault of the manufacturers for using the tests the Gov told them they MUST use and us for buying the cars that don't meet standards that disnt existin the past....

 

[GeeJayW]

And everybody has known for years that both the economy and emissions test were completely useless and came nowhere near to real world results but the state continued to mandate the tests. Now they have finally decided to introduce more representative tests its all the fault of the manufacturers for using the tests the Gov told them they MUST use and us for buying the cars that don't meet standards that disnt existin the past....

The thing is, you can spend time and effort developing a really good spanner to fit a particular nut. Then someone says you can use it as a hammer and knock some nails in. Yeah, you can, but it's still a spanner and not an especially good hammer. That's what has happened to emissions testing.

 

[Scott_F]

And everybody has known for years that both the economy and emissions test were completely useless and came nowhere near to real world results but the state continued to mandate the tests. Now they have finally decided to introduce more representative tests its all the fault of the manufacturers for using the tests the Gov told them they MUST use and us for buying the cars that don't meet standards that disnt existin the past....

I could be wrong and call me a cynic, but the fact that the tests enabled manufacturers to produce marvellous (but completely unrealistic) fuel economy figures for their cars leads me to suspect that they had considerable input into the design of the system that produced said figures.

 

[GeeJayW]

I could be wrong and call me a cynic, but the fact that the tests enabled manufacturers to produce marvellous (but completely unrealistic) fuel economy figures for their cars leads me to suspect that they had considerable input into the design of the system that produced said figures.

Not really. The methodology began in the USA by CARB, the EPA and later in Europe by various technical bodies. Clearly some input from the vehicle OEMs, oil companies, government institutions. The focus was on being able to repeatably and accurately replicate real-world driving in a laboratory in order to be able measure and understand exhaust emissions. Initially to try to understand and deal with photo-chemical smog that was prevalent in major cities, in particular Los Angeles and Athens. The smog was due to interaction between unburned hydrocarbon emissions and strong sunlight. They started out by measuring speed and time I profiles of actual drives around Los Angeles, the data was normalised and became the FTP-75 drive cycle.

In Europe, the same thing was done but in Athens, which led to the development of the ECE (urban) drive cycle. This is more stylised/simplified compared to the federal cycle and only goes up to 50km/h (30mph). As the demand for a drive cycle that was more widely representative of other cities, further on-road data was gathered which resulted in the EUDC or extra urban drive cycle which goes up to 120km/h (75mph). These were combined to create the ECE+EUDC, which included a 40s idle period before sampling began, followed by a further 11s before the wheels start turning. In about 1990, the 40s idle was done away with and the revised cycle was referred to as the NEDC (New European Drive Cycle). This is due to be changed for the new world harmonised cycle, but I've not been in the loop since the end of 2013, so am not sure just where things are up to.

Throughout the last 40 odd years, there has always been OEM vs regulators, where the OEMs have tried their best to get the most favourable results within the regulations, whilst at the same time the regulators make the testing more difficult and/or whilst reducing the permitted levels of pollutants.

The OEMs have sometimes taken things too far and have from time to time had their wings clipped. In the meantime, they have developed cars that are HUGELY cleaner, faster, safer, more comfortable, better equipped, more fuel efficient etc. than they were when all this started.

There's a lot of pub talk and fake news around this subject as well as political and financial vested interests. There really isn't a lot of honest factual discussion, unfortunately.

 

[Scott_F]

^I'm still not convinced but like I said I'm a cynic:

Your Money Their Tricks - Misleading MPG claims - BBC One

Obviously, the manufacturers know all the tricks that allow them to optimise the results but if the tests invariably produced unrealistically pessimistic figures you can be sure that they would have used their considerable lobbying leverage to have changes made decades ago.

 

[lfckeeper]

Shouldn't the 'real' mpg be really easy to do...

15 mins at 120kph with two slows to 110kph and back up to 120 kph(currently extra urban)

10 0-50kph back to 0 with 3 mins driving in between (currently urban)

All manufacturers have test roads so should be pretty easy. If someone complains they're not getting the 'advertised' Mpg dealer can explain its their right foot that's the issue not the car.

My CLS used to get almost bang on its advertised (I say advertised I mean what it says on Auto trader) figures...

I don't have a cat in hells chance of getting my 5 series claim of 65mpg. (it seems to get 52 - 53 mpg no matter what my journey ... I thought the OBC wasn't resetting at one point!)

 

[GeeJayW]

^I'm still not convinced but like I said I'm a cynic:

Your Money Their Tricks - Misleading MPG claims - BBC One

Obviously, the manufacturers know all the tricks that allow them to optimise the results but if the tests invariably produced unrealistically pessimistic figures you can be sure that they would have used their considerable lobbying leverage to have changes made decades ago.

Cynicism has its place I suppose and I don't really care if you're convinced or not. Please note, I have not said that I consider the fuel consumption figures published by the OEMs to be an accurate representation of what one might expect to achieve.

The vehicle OEMs employ very smart engineers. They are paid to develop cars that meet the prevailing global emissions standards and wherever possible give the company products competitive advantage. So that's what they do. Sometimes they overstep the mark, VW being a case in point. If the test was so easy, why would they feel the need to find a work around?

The BBC employs very smart journalists. They are paid to write news stories. So that's what they do. Don't for one minute believe everything you see or read in the media. Every story you will ever read or see will have 'an angle' laid out by the editor.

The exhaust emissions test was never designed to be a fuel economy test. It was designed to evaluate and develop exhaust after treatment systems for gasoline cars that by today's standards had crude fuel management systems and literally belched out unburned hydrocarbons and CO. It has developed since then and the current emissions limits are orders of magnitude lower than they were at the beginning.

The OEMs are well on top of the test methodologies and are always seeking ways to get the best results from their cars. So would you. Why wouldn't they? This is no different from any other form of competition...

 

[GeeJayW]

Shouldn't the 'real' mpg be really easy to do...

15 mins at 120kph with two slows to 110kph and back up to 120 kph(currently extra urban)

10 0-50kph back to 0 with 3 mins driving in between (currently urban)

All manufacturers have test roads so should be pretty easy. If someone complains they're not getting the 'advertised' Mpg dealer can explain its their right foot that's the issue not the car.

My CLS used to get almost bang on its advertised (I say advertised I mean what it says on Auto trader) figures...

I don't have a cat in hells chance of getting my 5 series claim of 65mpg. (it seems to get 52 - 53 mpg no matter what my journey ... I thought the OBC wasn't resetting at one point!)

The main issues are around getting the correct road-load model for the chassis dynamometer. When I was playing this game, we got very similar fuel economy results on the dyno compared to the road. Not always close to the published OEM figures though.

 

[zipdip]

Well I suspect even the most ardent save the planet person can understand that given the choice of saving the planet in a hundred years or actually being able to buy food in supermarkets will focus everybody's mind and the planet will come second,all this discussion of air quality has always puzzled me we as humans breath in oxygen witch is a corrosive substance,our lungs manage to overcome this menace and I am sure when faced with needing a knife to cut the air we breath mankind will find a way of removing all the impurities and turn it into a cases for mobile phones ,necessity is the mother of invention,all this playing with electric cars is just a fad,as were hydrogen powered ones,the people in charge know full well that to placate the green lobby they have to be seen to be doing something and the car driver is the easiest target,China and the far east will continue to pollute and every other means of transport will get a easy ride but the car driver will pay the price.

 

[GeeJayW]

Well, first of all we evolved to survive on breathing oxygen. So notwithstanding its chemical properties it's key to our survival and we have adapted to tolerate it, though I guess it kills us in the end if something else doesn't.

Without the internal combustion engine, power stations and jet engines (and I'm speculating here), there wouldn't be much NOx in the atmosphere. Outside of cities, local air quality is probably more influenced by next door's bonfire, wood burning stove, the power station down the road or that volcano going off in Iceland than it is by car exhaust. In cities, where there are lots and lots of vehicles and limited open spaces, exhaust emissions have an important impact on the cleanliness of the air people breath. In my view, the best way to solve this is to ban private vehicles from cities altogether. I'm guessing that would not be popular. Electric cars may ultimately become viable, but in my view there's a lot of work to do to get there in terms of battery technology, infrastructure provision. Overall though, cities need to have less vehicles for the road network to remain viable. Same applies to hydrogen vehicles.

The elephant in the room is that there are simply too many humans on the planet and the number is increasing every day. The demand on resources and the resulting increase in pollution is inevitable, until the time comes when our 'intelligence' is unable to keep it all going.

 

[SW18]

China and the far east will continue to pollute

I’m not sure China is polluting so much any more: an advantage of their political system is that it’s much faster to being about change when needed: the government took a decision to decarbonise and now China is changing fast. They are rapidly closing fossil fuel power stations and switching to renewables, aiming to become the world leader. And they are already the world leader in LNG trucks and high speed electric trains. It may take a while but China is looking like it might lead the way.

...every other means of transport will get a easy ride but the car driver will pay the price.

I’m not sure about this either: I can’t think of a means of transport that is not making moves towards lower emissions. E.g. haulage has been moving to Euro 6 for quite a while and in some countries is now going to LNG. E.g., despite lobbying, even London taxis have to change: already all new taxis have to be hybrid and there is a sunset time for diesel. Electrification of rail continues. Shipping is perhaps the slowest to change but it will get there, quite likely also with LNG.

 

[John]

Having seen how many hybrids are driven, with the accelerator pedal crashing through that thin veil of apparent emission-free smugness, I wouldn't be surprised if hybrids go nowhere near any claimed MPG figures in the real world either.

 

[Bobby Dazzler]

I could be wrong and call me a cynic, but the fact that the tests enabled manufacturers to produce marvellous (but completely unrealistic) fuel economy figures for their cars leads me to suspect that they had considerable input into the design of the system that produced said figures.

^I'm still not convinced but like I said I'm a cynic:

Your Money Their Tricks - Misleading MPG claims - BBC One

Obviously, the manufacturers know all the tricks that allow them to optimise the results but if the tests invariably produced unrealistically pessimistic figures you can be sure that they would have used their considerable lobbying leverage to have changes made decades ago.

It’s a test which never changes, the questions are open to anyone and everyone who is interested, and you can practice as much as you like. Even I could pass a test under those conditions

An engineer’s reason for being is solving problems. If you give an engineer a problem then they will find a way to solve it. And they’ll keep finding better solutions until you replace that problem with another one.

It surprises me that so many people were surprised to discover that cars are optimised to perform well in the test. They’re optimised in every other respect, so why not this one?

 

[grimree]

I read with interest all these posts regarding economy figures, and their accuracy (or lack of it) Does anyone believe the manufacturers figures? I would contend that they ALL massage their figures to get the best results and a comparison of the different figures will allow you to see which vehicle gives the best economy?

I'm sorry if I've repeated someone else's post

 

[GeeJayW]

I read with interest all these posts regarding economy figures, and their accuracy (or lack of it) Does anyone believe the manufacturers figures? I would contend that they ALL massage their figures to get the best results and a comparison of the different figures will allow you to see which vehicle gives the best economy?

I'm sorry if I've repeated someone else's post

What the OEMs do is complicated, but I do think they have similar goals and use similar methods to get the best results. So comparing (the abstract) figures between similar cars is probably a reasonable thing to do, just don't take them as absolute.

Most modern cars have enough sensors on board to figure out that they are being driven on a rolling road dyno. Front wheels going round, rear wheels stationary or vice versa is a big clue. Even when the dyno has four individual 48" rollers that simulate the road for all four wheels, the car can tell via the stability control system that the accelerations and deccelerations aren't 'real'. In addition, the speed-time profiles for the tests are well known and are easy to recognise, so again it's pretty straightforward to programme the car to figure out for itself that it is undergoing an official test. I don't know first hand, but this is what I think VW were doing with their diesels and as a result were using different injection timing, boost and EGR rate during a test compared to normal operation.

Now when testing a on a 2WD dyno, with the undriven wheels stationary, systems like traction control and ABS, Stability control and so on, will be kicking off trying to get control of those pesky driven wheels that are spinning. Some powerful cars I've tested had smoothing functions for cruise conditions on the road, but at steady speeds on the dyno, the car's control system fights the dyno control system which result in very unstable control.

So, in some cases it makes sense to turn some of these systems off when the car is being tested.

Another thing the OEMs seem 'good' at, is deriving an optimal test road-load profile for their car models. About 25-years ago, I built a spreadsheet physics model to calculate road-load profiles for cars based on their physical dimensions and some other details. The profiles that were generated correlated well with some on-track work that I did at the time and the corresponding dyno tests. It also stacked up very well with some similar work being carried out by an industry colleague in another test house. My profiles were however much 'heavier' than the profiles provided by the OEMs. They were also much heavier than the profiles provided by another different testhouse.

In short, due to the complexity of the test methodology there is space for interpretation that really wasn't the intention. A bit like Phil Mickleson's actions at the weekend at the US Open, some (maybe all) have chosen to use the rules to their advantage.