Technical Why Twinair never really worked

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Technical Why Twinair never really worked

As an economy enthusiast, I find that the people who bang on the loudest about fuel economy are the ones who understand it the least.

I mean, Andy's clearly never even accelerated at WOT while watching instantaneous MPG (to anyone who doubts this, go try it!), can't fathom the difference between l/hr and l/100km, doesn't understand energy densities and posted half a dozen other whoppers - that only another Troll would take the time to reply to.

The curtain has fallen.
 
I thought the whole point of a small fiat was to buy it and drive it like its on fire, enjoy it and still get 40+mpg
 
Do you have any opinion on the matter?

I think it's perhaps a little harsh to say the TA never really worked; from what's been posted on this forum, it's clearly brought a great deal of pleasure to many owners, some of whom still swear by it. A few owners never really got used to the somewhat quirky power delivery, and a much smaller number hated it so much that they quickly traded their cars away, usually at a significant financial loss. So the advice to potential purchasers to have a long test drive first (and preferably try to get hold of a car for a day) remains sound. If your primary focus is ecodriving, or having the lowest possible running costs, you'd do better to buy a 1.2 instead.

That it never came close to achieving its official economy and emissions figures is beyond question, but that was known (and well reported) right from the very first reviews, so anyone claiming to have been seriously misled hasn't done the kind of homework I'd expect from someone about to commit to a five figure expenditure. I think the whole economy issue is a red herring; for most, fuel will only be a small percentage of the total cost of TA ownership. The extra cost due to the difference in the figures is probably in the order of 2-3p/mile, and in any case real world economy is pretty much on the money when compared with other similarly performing cars of equivalent size and aerodynamics. In contrast, the last pcp figures I saw for a 105TA on a 6000 mile 48 month contract worked out at a whopping 52p/mile before servicing, insurance or fuel, so any difference due to fuel economy will be only a few percent of total running costs.

If I were a prospective owner, I'd be more concerned about long term reliability than economy; there have been enough turbo and uniair failures (and DMF failures on those so equipped) reported here to give some pause for thought. Not a deal breaker, and by no means that common, but not exactly unheard of either. I stand by what I've said from the outset; this is a car perhaps best bought new and traded away before the warranty runs out.

As to the future, I'd say the TA will turn out to be a somewhat quirky side branch on the Fiat Powertrain evolutionary tree; relevant at the time of its introduction, but probably not a design with a great deal of future for further development. I just don't think the way forward is in highly stressed high bhp/litre twin cylinder turbocharged petrol engines. If such designs are to have the kind of robustness we've grown accustomed to in the FIRE, then more money will have to be found for better materials and quality control than FPT are probably willing to spend. This one also appears to demand especially close attention to detail in its oil and other servicing requirements, at a time when the requisite skills are fast disappearing from both DIY enthusiasts and the garage trade alike.

Fiat took every advantage of the tax breaks and other financial incentives available in the UK at the time of launch; now that it would have to compete in the market without these, it remains to be seen whether this engine will ever be an option in UK 500's again.

The biggest losers from any misrepresentation were probably HMRC; if the car had been taxed in line with its real world CO2 performance, I doubt it'd even have made the (then) £30 RFL cut. But don't feel too sorry for them - they got all that back, and more, from the extra fuel duty they received.
 
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I thought the whole point of a small fiat was to buy it and drive it like its on fire, enjoy it and still get 40+mpg

Pretty much exactly sums up what I do and what I get with my 1.4 100hp 500 Sport :) Once warmed up, not taking it to 4-5 k rpm in each gear when accelerating goes against the spirit and character of the car. I always give it plenty of beans when driving conditions allow but average 38-41 mpg according to trip computer no matter how I drive the thing. Bombproof engine - mine turns 10 years old next week.
 
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I think the point here is...one side is stating maximum fuel use is a constant. So flat out at 5000 rpm in 3rd uses the same amount of fuel as flat out at 5000 rpm in 5th. The engine is seen to be in the same state regardless, but the action of the gearing effective gives more distance per "bang" so a better MPG figure despite a similar fuel flow?

Yes?
Basically yes! Nicely explained!

Although you missed one tiny detail. In 3rd gear the revs rise much quicker than in 5th gear. A turbocharged engine might in 3rd gear not be able to adapt the boost quickly enough to make it match with the boost in 5th gear. Different boost results in different fuel flow.
 
One graph from one 10 second time period that I can make in 5 minutes on excel doesn’t prove anything and certainly doesn’t have to have come from any real world data, we only have your word on that, and guess what you have a vested interest in proving yourself right.

Andy's clearly never even accelerated at WOT while watching instantaneous MPG (to anyone who doubts this, go try it!)

It is a shame that someone accuses me of posting fake data! Why on earth would someone post fake data when numerous forum member can easily check validity by just looking at their dashboard? Only someone really stupid would come to such idea.

It is a pity that this discussion went in the wrong direction. I only tried to nuance statements posted by others to come to a discussion about the real reason why the TA's fuel economy is somehow disappointing. Unfortunately that is impossible if someone blind of fury tries to refute every statement, even when it matches his own opinion.

I fully agree that the real-world fuel economy of the TAs (both Euro 5 and 6) is somehow disappointing, but there is another reason than the one suggested at the beginning of this thread.
 
Having just had my 5 year service on my 2013 500S TA, I was given a 1.2 500 POP as a courtesy car and whilst it looked similar it was NOT the same. I swear I could have pushed my feet through the floor panel and ran it faster, Flintstones style, off the line. 1st gear was OK but on getting to 2nd and with my foot on the floor it just slowly sped up. Forget overtaking anything, you could only do that when the other car was stationary. I swear it took about 30 seconds to wind itself up to 70 and even then it felt like it would not go much more than that. It might have been broken, but it only had just over 2k on the clock. And it had that annoying set speed stem just under the indicator/light stem which I kept on hitting almost every time I turned right...

I've never been more pleased to have mine back from having work done, ever. We brought our TA after the 4 year finance was up as we loved it so much, and a day driving around in the 1.2 utterly justified it. I live and work in the city, and being able to get in and out of tight spaces and out of junctions/do overtakes etc when required is a must. It's the most fun car I've ever driven with the biggest personality and I would buy one again without much thought and it's here I think the TA excels. Unfortunately not a lot of cars are sold, realistically, on the fun factor alone, so it's no surprise it's going away now.

In regards to the MPG like pretty much everyone else I only get between 43-46 mpg out of it, so nothing like what was stated on the blurb, but to me that's fine as I didn't buy it for the mpg. It's only been in eco mode about 3 times in 5 years and I think it was on those times when I thought I was running on fumes.
 
Did it deliver 67mpg or whatever they claimed - eh no. I think we’ve all worked that one out by now thanks, particularly those of us who actually own a TA.

I echo the above sentiment. Why are people fretting about official vs real mpg? The fact that automakers are using NEDC test to 'overpromise' fuel economy shouldn't rise an eyebrow.

Someone was talking about TA is failing its mission. Well, this has been my mission for the last several years: finding a 7-seater family petrol car with 40+ real life mpg. Finally I can rest, now that I've found 500L MPW with TA 105. It drives superbly, too. Except for the disappointing lack of power/torque at the start of 2nd gear, is anybody else irked by this?

Mission accomplished, thanks to TA. Now let's hope it will be reliable.
 
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If your primary focus is ecodriving, or having the lowest possible running costs, you'd do better to buy a 1.2 instead.

I think the whole economy issue is a red herring; for most, fuel will only be a small percentage of the total cost of TA ownership.

.........

Well written post, insightful and well-balanced.

I would argue, however, at your statement that fuel will be a small % of total cost of a car, as that figure surely depends on various factors such as whether you purchase a new or used car, your annual mileage and how long you keep the car. I, for one, have always been buying used cars, and as I have eluded on my previous posts, recently acquired a 14-plate 7-seater MPW for £6300 with only 24k on the clock. Good deal, I think.

I agree that we should be focusing on a more meaningful or wholesome metric of owning a car, such as total ownership or running costs. You quoted some pcp figures of 500 TA, I wonder if there are calculations out there comparing running costs of TA vs 1.2 (or 1.4 if 500L) vs 1.3 diesel? That would make an interesting analysis.

Fuel economy would favour 1.3D, though not by much I suspect. I wonder if maintenance costs of TA and 1.3D would weigh them down (expensive oil & turbo for TA and DPF/EGR valve and the like for diesel) and make the conventional petrol the winner, as you've suggested?
 
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For anyone who is interested, the Twinair is now back on the Fiat configurator. Presumably WLTP testing is now done, quoted mpg is now 60, which is at least acheivable with care.
 
I did! Several manufacturers temporarily deleted some models from their configurators, the WLTP testing facilities have been a bit overwhelmed. Only the 85 model is there at present, we'll see if the 105 reappears in due course.
 
One thing that puts me off the TA is it's complexity. They can be extremely hard to troubleshoot and experience is thin on the ground for these.
 
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