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Prius Nabs International Engine of Year Award for Third Year Running

For the third year in succession, the 1.5-liter gasoline engine of the Prius Hybrid Synergy Drive powertrain has won both the International Engine of the Year Award in the 1.4– 1.8-liter category and the “Best Fuel Economy” category. The awards were made at the Engine Expo in Stuttgart, Germany.

The 1.5-liter, four-cylinder, Atkinson Cycle gasoline engine with Variable Valve Timing with intelligence (VVT-i), produces 76 hp (57 kW) and 111 Nm of torque on its own. With the 50 kW electric motor, the Prius drivetrain produces a combined 110 hp (82 kW).

Since 1997, Toyota has sold 613,300 hybrid vehicles around the world. In Europe, Prius sales have rocketed, climbing from 8,136 units in 2004 to 18,886 in 2005—an increase of 132%—and are forecast to exceed 25,000 units this year.

The results of the International Engine of the Year Awards 2006 were decided by a panel of 61 automotive journalists from 29 countries. The awards have been held since 1999 and reward the best engines available on the market. Every engine in mass-production installed in a production car on sale in more than one country is eligible. There are 12 categories to distinguish engines by size, fuel economy and performance.

The other winners this year are:

Other International Engine of the Year Awards 2006
International Engine of the Year 2006 BMW 5-liter V10 (M5, M6)
(Second year in a row)
Best New Engine 2006 Volkswagen 1.4-litre TSI Twincharger (Golf)
Best Performance Engine BMW 5-litre V10 (M5, M6)
Sub 1-liter Honda 1-liter IMA (Insight)
1-liter to 1.4-liter Volkswagen 1.4-litre TSI Twincharger (Golf)
1.8-liter to 2-liter Volkswagen 2-liter Turbo
(Golf, Audi A3, A6, SEAT Leon, Skoda Octavia)
2-liter to 2.5-liter Subaru 2.5-liter Turbo
(Impreza, Forester, Saab 9-2X)
2.5-liter to 3-liter BMW 3-liter Twin-Turbo Diesel (535d)
3-liter to 4-liter BMW 3.2-liter (M3, Z4 M)
Above 4-liter BMW 5-liter V10 (M5, M6)



Would it have been there if it wasn't attached to a hybrid drivetrain? Is it realy that good an engine?

Michael Slavitch

Yes, because the innovation is the flat power curve that offers maximum gasoline efficency, while using the batteries to provide horsepower and torque. The result is efficiency and emissions that far better than an engine of similar displacement that needed to operate under a full power band.


Seems strange that they de-tune the 1.5 litre from 106hp (in the Yaris) to 76hp for the Prius. It begs the question why not use the 1.0 litre from the Aygo/107/C1 that produces 67hp if all it's really doing is keeping momentum, since the motor has instant torque.
I am sure I read an article that a journalist from the Sunday times got over 85mpg with this engine...

Good old google -,,22750-1794324,00.html (it was the toyota engine in the C1)

Or indeed use the 86hp 1.3litre for more pull, though thats more than the currently offered with the 1.5??


It is not strange at all. They did not "de-tune" the 1.5 litre engine, they used the so-called Atkinson cycle (actually a Miller cycle) to get excellent thermodynamic efficiency, but at the expense of power, which is compensated for by the electric part. Saying that some journalist got over 85 mpg (Imperial gallons) with a 1.0 litre petrol engine means nothing, since it was not at all the same car.

All this is perfectly logical and really deserves the award ; they did not "forget" any simple idea. :-)


The idea of Atkinson and Miller cycle is very simple: by arranging late intake valve closing effective expansion ratio of the engine is higher then effective compression ratio. More mechanical energy is drawn from expansion of hot gases, and efficiency goes up. Miller cycle in addition employs turbo- or super- charging. Virtually all industrial diesel engines (where fuel efficiency is most important) use to some degree Miller cycle.

For vehicle application, where stoichiometric gasoline engines are sized for high acceleration performance, these engines actually have lower fuel efficiency at almost closed throttle (highway cruise) because of overexpansion. This phenomena appears during real life vehicle use, not during governmental fuel efficiency tests. I strongly suspect then overcooling of exhaust at this condition also makes 3-way cat inoperational.

Now: Toyota Hybrid Synergy drive system with electromechanical infinitely variable transmission allows the engine to run at low RPM and more open throttle at all conditions, even low-speed cruise, thus enabling effective use of Atkinson cycle gasoline engine. This is the beauty of their technology.

Displacement of the IC engine is traditionally calculated as swept volume of a piston. In Atkinson cycle effective amount of ingested air is much lower, and in addition the engine is tuned to be most fuel efficient - low RPM, and does not use tuned air intake. In fact, according to amount of ingested air, it is closer to 1 liter engine, not 1.5 liter. Since low power output per liter displacement.

2. Nice to see the appreciation of automotive press for BMV and VW engine developments. Pointed in right direction, these fooling around German Engineers could work miracles….


2. Nice to see the appreciation of automotive press for BMV and VW engine developments. Pointed in right direction, these fooling around German Engineers could work miracles….

What, like this: (Click on the english traslation at the bottom)

84 mpg (US) with no need for hybridization. Cheap as well & rear wheel drive.

Light weight and simplicity are the way forward.




Get real, man



I'm curious what is it that you think is unachievable about this concept?

After all a Diesel Smart car already in production in Europe can already achieve 67 mpg (US). And that car is about as aerodynamic as a house brick. It could easily be improved upon.


fyi CO2

Last time I checked, the Smart Car is for 2 passengers and room for a loaf of bread: great commuter car, but not practical as a family vehicle. I'll stick with my Prius, and forego the "clean" diesel.


Do not forget the way these guys did the test:

1. They drove to the filling station, filled it up and got underway. So that means the engine was warm.
2. They used all the tricks to minimize consumption.
3. They never got above 50 mph, even better, it seemed the traffic was heavy and they couldn't even reach 50 mph all the time.
4. If they stayed on the left lane, how much slipstream did they pickup behind the trucks?

If I do all these things, I am sure my Prius does better than 90 mpg.

The Prius figure mentioned in the article is according to the standard Euro test, which prescribes a cold start and certain speeds and accelerations, which is completely NOT what these guys did in their C3.

Get your facts first, and then you can distort them as much as you please (Mark Twain).


fyi CO2,

I wasn't referring to the Smart car, I was referring to the Loremo, which, in a fashion is a four seat car. Although I'd consider it a two seater coupe with a generous load bay.

If a diesel Smart, can get 80mpg (without special driving) then a much lighter and aerodynamic car should easily be able to break 100mpg (UK mpg that is)

My beef with the Prius is that here in the UK, its damn expensive. For the same money I could buy a much better handling quicker diesel for the same money.

And, besides, I'm not in the market for a £20K car, I'm in the market for a £10K car.


fyi CO2


Maybe you should consider a 2 year old Prius.
You can't get better handling of the earth. Drive smart and try to keep those diesel particulates to a minimum.

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