US & European Fuel economy rating

For the 2010 Prius

European:
Combined city / highway: 3.9 ltr/100 km = 25.6 km/ltr = 60.3 mpg

US:
Combined city / highway: 50.0 mpg = 21.3 km/ltr = 4.7 ltr/100 km


In Europe they are using fuels with 95 octane (they do not have less than that). Here in the US 87 octane fuels. Would that be the reason for the 10 mpg difference?

Not your numbers, but another problem with 'European numbers' is that they may use an imperial gallon, 5/4 of a US Gallon. There was a 88.5 MPG micro-car diesel blurb the other day that used imperial gallons and the European test. Very impressive, until you realize that a Prius using the European Test and imperial gallons gets 73.3 MPG in a midsized car.

You are correct. Our 95 octane Basic corresponds to the 91 octane U.S. Premium. Details can be found here:

[ame=http://en.wikipedia.org/wiki/Octane_rating]Octane rating - Wikipedia, the free encyclopedia[/ame]

There are also other threads on this topic around.

No, it is not because of the higher octane fuel. On the contrary, you usually get *worse* mileage when using higher octane fuel, as it has lower energy density (you can find other threads on this here). It is because of different testing cycle (I would say ).

Entirely because of the different testing cycle and parameters. Our numbers come straight off the dyno while the US EPA discounts their numbers a bit; in addition, the US test cycles were always stricter anyway, and now include sustained high speed/high acceleration driving, use of air conditioning, and cold temperature running.

You can find out more about the EU tests at VCAcarfueldata.org.uk - Fuel Consumption Testing Scheme, and about the EPA tests at Fuel Economy Test Schedules.

The numbers for the Prius on the UK test, from Gen 2 to Gen 3, improved 10% in the 'extra-urban' part of the cycle and 28% in the 'urban' part. I believe this is down to the exhaust heat capture system on the new car - we didn't get the coolant thermos on Gen 2.

Earlier European test cycles had figures for city traffic, country road traffic (80 km/h) and highway traffic (120 km/h). The present highway figures are not very realistic in my view, an average speed of 63 km/h on the highway is not highway speed in my view. When I drive home form our head office, I will drive at appr. 130 km/h for 2 hours, and then you will have a very different fuel consumption. In fact many modern European petrol or diesel cars of the same size will have a better fuel consumption than the Prius in these conditions. The Prius really excells in city traffic, there the hybrid drive has a real advantage, not in constant speed situations on country roads or highways.

I did start my post with "Not your numbers" as he had them correct, I was merely pointing out additional dangers comparing the two sets of mileage.

Which country do they use km/l rating?
last night on a 80 km trip with the cruise set at 104 km/hr the OBC read out was 3.9 l /100km

Is there many threads on the forum about how much better metric is for units measurements :boink:

The revised, USA EPA and existing Euro testing profiles have different speed profiles. For example, the Euro speed profile on goes above 45 mph for a brief period of time, less than a minute. The Ford Focus hybrid has a hybrid transition speed of 47 mph and the 2010 Prius, 46 mph. Neither hybrid has to run in engine-only mode during the Euro test except for about one minute out off a nearly 20 minute test. In contrast, the revised USA EPA test has extensive high speed, cold weather and air conditioning phases added.

Bob Wilson

Japan, the home of the Prius .

The U.S. rating is much more realistic. Here in Europe, a lot of people struggle to get the advertised numbers (in any car) and are disappointed in result :tinfoil3:. In contrast, the EPA rating is relatively easy to achieve.

I've never been a great fan of any of these mileage tests because they don't give the driver enough information to drive the performance of their car. In contrast, if we had a graph showing 'mpg vs MPG', it would be trivial for owners to drive within the optimum, performance window of their vehicles. For example, here is the 55, 65, and 75 mph (88, 104, and 120 km/h) curve for six vehicles:

This chart tells drivers different things:

• 1.5L Prius owners - 65 mph is the knee in the curve, above this speed, mileage falls off
• 1.8L Prius and Jetta TDI owners - 75 mph is fine, we don't know if there is a knee (my charts indicate 75 mph is the 1.8L Prius knee)
• 1.3L Honda owners - 55 mph is probably the fastest you really want to run at for excellent mileage, it falls off rapidly.
• 1.5L Yaris owners - it doesn't matter, bring cash for gas

This type of information not only lets buyers make informed decisions but having bought their ride, get the most they can. It helps them after the purchase.

Bob Wilson

Yes, I totally agree that this type of information is much more useful. However, you still need some simple numbers for the "Joe Public" to enable him to make a simple comparison, I think. Anyway, thanks for that chart, it is very useful!

Which models are NHW11, NHW 20 and ZVW 30

Gen I, gen II and gen III Priuses

You are right, I am aware of that. But because NHW10 was sold in the Japan only and NHW11 is commonly reffered to as the "gen I" in the US, i put it in this simplified way .