Technical Why Twinair never really worked

[AGH1965]

What’s really insane is asking someone to answer a question based on the data you provided then disagreeing with that answer, despite having posted the data yourself that proves the rule.

The average is even there on the page for you to see! 6.03l/100km or 46.86mpg

Sorry for the misunderstanding. Your analysis isn't insane at all!

I meant the outcome, these 44 mpg. I find such a value insane for such a car. I don't know what you need to do to reach such a poor average.

The 44 mpg also surprised me a bit, but the average shown by the website is clearly not correct. Thank you for making that clear.

However, of the 53 cars only 33 are within the 44 mpg +/- 10% range. My previous TA isn't.

Personally I wouldn't like official values that can be beaten that easy. Please let them be challenging. They should show what the car is capable of when driven by a pro who exploits the car's full potential. Otherwise you make the brainless think that they are really good drivers.

 

[StevenRB45]

I had a 2litre 130bhp 1996 Saab 900 that would average more then 33mpg in regular use, which is a shocking comparison to a much smaller much lighter much newer Twinair engine of a 500.
.

To be fair to it..I wouldn't call this regular use in the conventional sense. I sold the aforementioned Suzuki having destroyed 3 wheel bearings, 3 sets of wish bones all 4 shocks and it did start emitting black haze on full throttle as well at 75k.

I may have grown up a lot since then..but I still find it bonkers something with so little power can use so much fuel.

 

[AGH1965]

In 2011 I had contact with the guy who reached the 33 mpg average shown on the website we discussed above. He sold the car rather quickly because he was dissatisfied about the fuel consumption. He said that his Audi TT used less fuel when driven similarly. When I asked about his driving style, it appeared that drove quite often 100+ mph.

 

[PuntoHowTo]

To be fair to it..I wouldn't call this regular use in the conventional sense. I sold the aforementioned Suzuki having destroyed 3 wheel bearings, 3 sets of wish bones all 4 shocks and it did start emitting black haze on full throttle as well at 75k.

I may have grown up a lot since then..but I still find it bonkers something with so little power can use so much fuel.

If you look back, I wasn’t referring to the Suzuki (although it does sound like you murdered it) the 33mpg was your reference to your only experience of a Twinair.

 

[StevenRB45]

If you look back, I wasn’t referring to the Suzuki (although it does sound like you murdered it) the 33mpg was your reference to your only experience of a Twinair.

I got that...but I thought a better provide a bit of back ground as to the "regular use" required to get 33mpg out of a TA.

 

[PuntoHowTo]

Personally I wouldn't like official values that can be beaten that easy. Please let them be challenging. They should show what the car is capable of when driven by a pro who exploits the car's full potential. Otherwise you make the brainless think that they are really good drivers.

Well no, that’s not right at all, they should reflect what the average driver should expect to achieve.

The whole problem with the TA (and other small engine turbos) is that it’s impossible in every day driving to achieve the figures they are quoting as fuel economy figures for that car.
Putting some pro in to “explot the car’s full potential” is either going to yield the same sort of results that we already have, or if thrashing the car is going to go the other way.

The tests should reflect an average driver on an average journey.
Currently they quote 67mpg for the TA where as if the average is actually only 44mpg, then owners are paying 50% more in fuel bills than they were promised by fiat when they bought the car, which goes back to the original point of this whole thread. The TA and other small engine turbos are not built for economy in the real world, they are built brilliantly to only achieve good results on a standard test.

Everyone bitches about VW and their “defeat device” but this is just as big a deal, if not worse as Fiat won’t be patching their software any time soon.

Everyone is now giving up on diesels because the media totally slated them Following dieselgate, and they are saying that petrol cars are now just as clean from a CO2 stand point, but that’s clearly a long way from the truth when petrol cars consistently fail to meet their supposed achievable mpg/CO2 figures.

 

[PuntoHowTo]

I got that...but I thought a better provide a bit of back ground as to the "regular use" required to get 33mpg out of a TA.

I was in my 20s when I had the Saab, I didn’t exactly go easy on it, although it survived much better than its Suzuki counterpart, on one occasion driving me to the nearest garage 8 miles away when a brake pipe burst (brakes still worked when I got there) the only other thing that went wrong was the rear brake discs crumbled due to rust and lack of use before I bought it. A very easy fix to swap the discs over.

That was it, owned it for 4 years nothing else went wrong with it despite the constant abuse.

 

[AGH1965]

they should reflect what the average driver should expect to achieve.

Why? The average driver doesn't use S&S, doesn't follow the instructions from the gearshift indicator and doesn't coast in gear when possible.

Coasting in gear is one of the strengths of the TA. The friction and scavenging losses of this tiny engine are that low, that the car hardly slows down when coasting in gear. The cars behind you will probably not even notice that you are coasting. And when doing so, the gearshift indicator warns you to shift down on time before the fuel injection restarts. Using this plus S&S makes it possible to reach reasonable fuel economy in city traffic.

Every now and then I have to make a 5 mile journey with cold engine through the city. According to the tripcomputer I manage to reach 6 l/100km or less (47 mpg or more) driving the way I explained above. To be clear, that is with accelerating normally and without being a burden for other road users.

FIAT made a car with such potential. People who choose to ignore that shouldn't complain about the car but about themselves. Therefore I see no reason why official mpg figures should be representative for the average driver.

 

[AGH1965]

Slightly off-topic, but I like to clarify something we discussed about earlier.

The 44 mpg also surprised me a bit, but the average shown by the website is clearly not correct. Thank you for making that clear.

Both the average of 6.4 l/100km (44 mpg) and the one of 6.03 l/100km (47 mpg ) are correct for these 53 cars.

The average of 6.4 l/100km is what you get if you calculate the mean value of the 53 average fuel consumptions.

The average of 6.03 l/100km is what you get when you base the calculation on the all kilometers and all litres of all 53 cars. That means that the cars with more kilometers have more influence on the result than those with less kilometers.

 

[Twinkletwinklelittlestar]

Perhaps a useful addition to how the data is presented to us would be for the testing results to add a +/-. So rather than just ‘n mpg city, n mpg distance, n mpg combined’ they could add ‘with this engine expect up to +5% or -25% depending on driving style’. For little turbo engines the % are likely to be as suggested, for larger non turbo engines would anticipate the + could be bigger and the - smaller. Ditto diesels. Just an idea.:idea:

 

[306maxi]

I've got to ask: if that's the case, then how on earth are some cars so insanely heavy? For example, surely land rover could've designed the previous discovery so it weighed rather less than 2.7 tonnes?

It’s a big car with a big engine and there’s a need for it to be rugged. It was also based on slightly old construction technicques and materials. It will also have significantly more features than a 599 and is going to weigh a lot more. It’s just the way it works.

 

[PuntoHowTo]

Coasting in gear is one of the strengths of the TA. The friction and scavenging losses of this tiny engine are that low, that the car hardly slows down when coasting in gear. The cars behind you will probably not even notice that you are coasting. And when doing so, the gearshift indicator warns you to shift down on time before the fuel injection restarts. Using this plus S&S makes it possible to reach reasonable fuel economy in city traffic.

Coasting in gear is how learners are taught to drive in the uk, so the majority of people will drive like this (hear at least) also most people will not bother pressing buttons if it makes not real difference to their day, most people will leave stop start switched on (a prime example of this are people still driving about with rear fog lights on a week after there was any fog.)

Your opinion is largely irrelevant as the new tests, DO test the car in average use by an average driver on a real world road, they are not being driven by some hyper mile nut trying, infact the manufacturers are deliberately now trying to get their cars to perform badly, for fear that in the future the eu will keep constantly demanding ever more impossible to achieve figures.

 

[AGH1965]

Your opinion is largely irrelevant as the new tests, DO test the car in average use by an average driver on a real world road

No, you are completely wrong. The new test that is used to determine official mpg and CO2 figures is a test on a chassis dynamometer, just like the old test was. The test cycle is called 'WLTP'. You confuse the new test with RDE testing. That kind of testing is indeed done on the road, but it only has a ‘not to exceed limit’. So it is not used for determination of any official figures. It is just an additional check to track down 'defeat devices'. More information can be found on the official EU legislation website, but this and this is better understandable.

Coasting in gear is how learners are taught to drive in the uk, so the majority of people will drive like this (hear at least)

People will coast in gear, but just the last part as they are used to do with other cars. When driving TA you can start coasting very much earlier, since the car hardly slows down compared to other cars. With the TA you can extend coating in gear by at least 200%. That is what makes the difference. Unfortunately hardly anyone recognises this capability of the TA.

most people will not bother pressing buttons if it makes not real difference to their day, most people will leave stop start switched on

Indeed most people leave S&S switched on, but they simply use the clutch to sabotage S&S.

 

[PuntoHowTo]

People will coast in gear, but just the last part as they are used to do with other cars. When driving TA you can start coasting very much earlier, since the car hardly slows down compared to other cars. With the TA you can extend coating in gear by at least 200%. That is what makes the difference. Unfortunately hardly anyone recognises this capability of the TA.

Indeed most people leave S&S switched on, but they simply use the clutch to sabotage S&S.

I’m bored of repeating myself and you making completely unfounded assumptions, we don’t need to keep going round in circles, the proof is in the data you provided, everything you’ve posted above is your opinion of how most people drive, I’m fairly certain I’m right in saying you’ve not sat in with 53 drivers of one specific car and analysed their driving habits. It just seems like you want to continue arguing over anything you can grasp at.

 

[AGH1965]

I’m bored of repeating myself and you making completely unfounded assumptions

Isn't that the pot calling the kettle black? You continuously repeat your assumptions about legislation, although you clearly don't have a clue.

When the Dutch 500 forum still existed, I was an active member and I heard a lot from other 500 drivers about their driving style. Pros and cons of coasting in gear, using S&S and obeying the gearshift indicator were extensively discussed among TA owners. Therefore I don't think I'm making completely unfounded assumptions at all, unless the British are very different drivers.

 

[PuntoHowTo]

Isn't that the pot calling the kettle black? You continuously repeat your assumptions about legislation, although you clearly don't have a clue.

Where have I even posted any assumption about legislation?
#graspingatstraws

 

[StevenRB45]

I might be geographically stereotyping "the dutch" here...but would that be "the dutch" as in people who live in the flattest country in Europe?

Hills don't half make a difference to fuel economy..

 

[AGH1965]

I’m fairly certain I’m right in saying you’ve not sat in with 53 drivers of one specific car and analysed their driving habits.

You are right, but at least 15% from the 53 drivers from this list were members of the long gone Dutch 500 forum. That were exactly the people who told me a lot about their driving habits, very different driving habits. And to be honest, I didn't exploit the TA's capability to coast in gear seemingly endlessly until one of those 53 drivers who told me about it.

Where have I even posted any assumption about legislation?

Well, you wrote several incorrect things about legislation, but I think you assumed to be right. Therefore it were assumptions, my friend.

I might be geographically stereotyping "the dutch" here...but would that be "the dutch" as in people who live in the flattest country in Europe?

However, because most of the country is below sea level, we have an awful lot of very short hills called dikes. If you add all these hills together, then you have Mount Everest.

 

[StevenRB45]

However, because most of the country is below sea level, we have an awful lot of very short hills called dikes. If you add all these hills together, then you have Mount Everest.

Perhaps..however I sincerely doubt any of the dutch cars ever encountered anything like my commute..which is 2 miles flat, followed/preceded by 4 miles in which you gain/lose 550 feet of altitude and .5 mile of gaining/losing 150 feet altitude. Downhill sections "coasting in gear" translates to "riding the brakes all the way down using energy to heat the wheel arches" and uphill well it's all 60mph so in a 85bhp TA you'll be taking big bites of the pedal on the right just to keep up with traffic.

Will say my wife's turbo diesel and turbo petrols have struggled to get anywhere near their figures with this usage, strangely my naturally aspirated car gets within 2.5 mpg of the official figure doing it though.

Now I understand everyone lives where they live and has their own commute..Fairly sure with Andy's figures his commute is a lot flatter than mine and at a steady speed. But it might not be people being careless when driving, it could be people live places where a small turbo engine is heavily on boost for several miles at a time.

 

[PuntoHowTo]

Well, you wrote several incorrect things about legislation, but I think you assumed to be right. Therefore it were assumptions, my friend.

[SARCASM] oh well that told me, how could I have been so silly [/SARCASM]