BASF Plant Science and Monsanto Add 5th Crop to Collaboration in Maximizing Crop Yield; Investing Additional $1B
Total to Acquire UTS Corporation and Its 20% Interest in Fort Hills Oil Sands Project for C$1.15B

Fiat Introduces 2-Cylinder TwinAir 85 HP in Fiat 500

Cutaway of the 2-cylinder TwinAir 85 HP. Click to enlarge.

Fiat’s new two-cylinder TwinAir engine family made by Fiat Powertrain Technologies (FPT) made its debut with the TwinAir 85 HP in the Fiat 500 today. Fiat had previewed the two-cylinder at the Geneva show earlier this year. (Earlier post.)

The gasoline-fueled 85 hp (63 kW), 900 cc turbo two-cylinder features a small-sized turbine which, combined with dedicated valve management strategies, minimizes transient response times and keeps maximum power levels high. The TwinAir 85 HP also comes with “Start&Stop” as standard. Compared with a 1.2-liter 8v engine, the new 85 HP turbo has 23% more power and a 30% better performance index. The performance of the two-cylinder is not only equivalent to a 1.4-liter 16v engine, but fuel consumption is 30% lower.

Fiat 500 TwinAir 85 HP
Bore x stroke (mm) 80.5x86
Displacement (cm3) 875
Valves per cylinder 4
Compression ratio 10.0:1
Max. power (kW) 62.5 @ 5500
57 kW @ 5500 with ECO button
Max torque (N·m) 145 @ 1900
100 @ 2000 with ECO button

Equipped in this way, the Fiat 500 reaches a top speed of 173 km/h (108 mph) and accelerates from 0 to 100 km/h in 11 seconds. Fuel consumption and emissions are 4.1 L/100 km (57 mpg US) and 95 g/km respectively (with manual gearbox), and 4.0 L/100 km and 92 g/km with a Dualogic robotized gearbox.

The Fiat 500 with TwinAir 85 HP also features an ECO button. Two driving modes can be selected: Normal and ECO. In the first mode, the ECO function is off and the engine delivers the maximum available torque (145 N·m / 107 lb-ft). Steering assistance is also specifically calibrated for Normal mode. No indication appears on the dashboard in this mode (City is not selected).

In ECO mode, torque delivery is cut off to 100 N·m (74 lb-ft) at 1750 rpm to minimize consumption and promote a driving style more suitable for city traffic. The steering wheel is lighter (CITY mode is automatically selected). The driver only needs to press the specific button on the dashboard to activate the ECO function. The lettering ECO will appear on the panel (the letter “E” will appear on the panel if the car has a Dualogic robotized gearbox). The Dualogic shifting strategy also switches to ECO mode to further optimize fuel consumption.

Compared with a medium-sized four-cylinder of equal performance, the new engine is significantly shorter (-23%) and lighter (-10%), opening the way to further developments, such as methane fuel supply or hybrid technology combinations. The soon to be available methane version of the TwinAir will feature a pair of special injectors in addition to the gasoline injectors on the intake manifold ducts.

MultiAir. The two-cylinder implements the MultiAir technology developed and patented by FPT, which was introduced on FIRE engines last year for the first time. The heart of MultiAir is a new electro-hydraulic valve management system that reduces fuel consumption by controlling air directly via the inlet valves (without using the throttle). MultiAir reduces polluting emissions (thanks to combustion control) and also considerably improves performance by boosting driveability with respect to a traditional gasoline engine of equal displacement. (Earlier post.)

Advantages of MultiAir technology applied to gasoline engines include:

  • maximum power boosted by 10% compared with a traditional engine of equal size;
  • 15% more torque at low rpm and during transitions by applying early intake valve closing strategies to maximize the air introduced into the cylinders;
  • less fuel consumption and consequently lower CO2 emissions, equal to 10% by eliminating pumping losses and precise parameter calibration for optimizing combustion;
  • lower polluting emissions from the engine by optimizing valve control strategies during the intake stroke;
  • prompter response to accelerator commands due to the constant air pressure upstream of the cylinders combined with extremely fast control of the intake valves.



Simpler economy.


A lot better mileage than the Chevy Volt!


Good job! All those innovations to get the consumption and emission down to 92 g/km.

On the other hand, Prius (bigger car) has even lower consumption with 89 g/km, 49 hp and faster.


A two cylinder engine like this could be a good range extender for an EV, if optimized for certain rpm.


Prius is a nice car but you can never achieve the fuel consumption promised by Toyota. I do not know if they use all possible loopholes of the regulation or what the problem is but real-life fuel consumption is proportionally higher for hybrids than for conventional cars. This is probably not the Fiat case, so real-life fuel consumption could be lower than for Prius. Thus, the Fiat achievement is remarkable. However, I am a little sceptical to the NVH characteristics of a 2-cylinder engine, so I would prefer 3 cylinders although one would have to sacrifice a couple of grams in CO2 in that transition.

Roger Pham

@Peter XX,

My Prius II routinely gets 55mpg combined driving in the falls and springs. For summers and winters, it gets around 52mpg, due to the use of AC and heating. I drive more freeway than city. If my driving is to have a higher mix of careful city driving, I'm sure that ~60 mpg is within reach.

This 2-cylinder engine in the Fiat 500 is a remarkable achievement. If a full-hybrid drive train is equipped, I'm quite sure that higher mpg can be obtained.


@Peter XX,
I also got 52 mpg in my 2008 Prius before upgrading to a plug-in. I've averaged 68 mpg ever since (total miles divided by total gallons). It really depends on how you drive and the conditions in which you drive. The new Fiat engine is a very exciting achievement. I agree that it would be great as a range-extender or in a hybrid.


Actually Peter there are people who get greater than advertised EPA mpg, getting 70 and even 100mpg in a Prius, in everyday driving. [the world record on a closed course is 136 miles per US gallon (1.73 L/100 km; 163 mpg-imp)] The thing is, the Prius has a gauge that tells you what you're getting while you're driving so you can learn to get more over time.

Bud Johns

I've got 108,000 miles on my prius and still have the original brake pads, which still look great. That means I'm pumping up the battery around town. It matters how you drive. I do about the same as roger. I does help to own a prius instead of just commenting on what you've heard. I applaud fiat for a very practical small car, I wish they had commented on who they smoothed the straight twin...


Smoothing a straight twin is no problem. Lot's of motorcycles have had very smooth straight twins for years.

I've been trying to figure out if they will sell this Twinair version in the US.

What would really work good is Multijet + Twinair = Twinjet (diesel twin)
and mild hybrid. Seems like a twin Diesel should halve the cost of most of the pricey parts. Add a simple regenerating alternator-starter, and a small Li-.. primary battery. Should do well over 100 MPG easy.

Thomas Lankester

Seems like the Prius regularly achieves or exceeds the stated fuel economy. Would you please back up your assertion as it seems to fly in the face of the facts (as per your assertion about Li battery EVs not being deployed cf

For the record, our 2000 (mk1.1) Prius is supposed to get 50 mpg(imp) ( but this year (its 10th!) we are at 50.6mpg after the coldest winter in the UK in 30 years. For a full year we normally get 52 mpg (imp).


A lot of buyers/drivers do not like such little cars.

1st (years ago) - gas was cheap.

Then, little cars got heavy and costly - a Corolla costs about the same as a Smart and gets almost as much mpg.

This thing might turn the tide if the US mpg are really anywhere near 57 mpg.

the doctor

This new engine is the right solution to many problems, while GM is just starting to work on aluminum blocks and chrysler still wants to put out big engines. Fiat would give Ford a run for their money if they werent cursed with that Chrysler albatross .
As for the arguments about Prius EPA mileage, please remember the numbers are for comparison only, they are calculated for 90% of cars and measured for only about 10% of cars and thats done on dynamometers with corrections for resistance etc. They arent real life and vary for every driver.


Prius fuel economy
Well, I do not drive a Prius myself so I only refer to the tests I can read in magazines. Note that this is in Europe, where the fuel consumption is according to the NEDC test cycle; it might be different in the US. I also refer to sources in the German TÜV, who have tested this car on chassis dynamometer. Eventually, it is apparent that Magazines never achieve the advertised fuel economy. One explation might be that they are driving much "tougher" than the driving cycle and/or that they drive more on motorways. Hybrid drive systems are not as efficient under those conditions. Besides that, I think Toyota does everything they can to "cheat" the driving cycle. You can always find some people who exceed the fuel economy rating.

fred schumacher

It appears the Fiat 500 with this engine will be able to equal Prius level fuel economy but at nearly half the price. The lower the cost of conversion to lower fuel consumption, the faster the transition can take place.

A Fiat 500 Twinair with a high-roof station wagon body would make a great urban delivery or rural go-fer vehicle. I would hope this engine will end up in the U.S.


If you could mate the engine with a dual clutch transmission with integrated motor, that would be good.

You could ditch the turbo and set it as an atkinson cycle genset, it should be able to give you 20kW @ 35% efficiency

Roger Pham

Hi Peter XX,
For reference, I also have a 1997 Toyota Camry 4-cylinder and with the same style of driving, I got around 26-27 mpg out of it. The Prius has about the same payload rating as the 97 Camry, but twice the fuel efficiency when driven similarly. This means that HEV's can increase the fuel efficiency by 100% for comparable vehicles. Not bad!


Gee...wasnt it just a few years ago GM was partners wit these guys. GM has a "new" generation of V8s coming out and the Volt. Too bad. Lutzed again.


Peter XX, go to Prius owner websites and find out ownership experiences rather than from magazine test drives.

You already got many owner account of their fuel economy. I don't know about you but I don't drive like magazine reviewers. I drive in the real world on real roads. I beat EPA figure in my Prius and most of my miles are on the highway.


I guess mostly those who achieve good fuel consumption report to those websites. Credibility cannot very high for such data, so I never even bother to look for such data on the Internet. If you are interested, I could do the same, i.e. give you my data. I am driving a BMW 320d. It does not have a hybrid system but it still gives me 5o mpg in normal driving. And, I can guarantee, it is much more fun to drive than a Prius. Anyone who has a Prius can challenge me so we could make a comparative test in convoy driving or any other preferred method. Then we could assess if the Prius is so good as some of you say.

People I have talked to tell me the opposite, i.e. they never get the fuel economy advertised. I have not yet met (in real life, not on the Internet...) one single Prius owner who has experienced better fuel consumption than the manufacturers data. Maybe this is a coincidence and maybe I have not talked to that many drivers but I hope you now can understand my doubts about these figures.

Roger Pham

Peter XX,
The BMW 320d has the latest in engine and diesel technology, with turbocharging. It is also a mild hybrid HEV, with stop-start feature, and selective alternator feature that only charges the battery during low load. The power steering is electrical to save power. Combining fuel-saving diesel's latest technology with gas-electric hybrid features, and the fuel efficiency will be spectacular.

Is the 50 mpg number represents Imperial gallon or US gallon? Also, diesel fuel has 13% higher energy value than gasoline. This is not to minimize the great achievement in the BMW 320d, just put things in persepective.


Peter XX,

Given that you only get about 10 US gallons of diesel per barrel of oil and 20 US gallons of gasoline (petrol) per barrel of oil, I would argue that for a gasoline engined hybrid like a Prius to return 50 mpg is actually much more significant than a BMW 320D to return 50 mpg. Not just because of the fact that diesel contains 20% more energy per gallon, but the fact that there is more gasoline in a barrel means that the best utilization of the petroleum is to use gasoline for passengers cars and diesel for trucks and buses.

Hopefully, at some point, we can have gasoline used on a diesel cycle to push its thermal efficiency over 40%.


The comments to this entry are closed.