Toyota Revises 2010 Prius Mileage

I guess I'll be "that guy" and say that this is disappointing. The existing Prius is already a winner in the city for anyone who bothers to put the slightest effort into it. The old EPA of 60mpg is quite doable. The highway is where the current car has trouble, and that's what they needed to fix (and I thought they said they had?) in a big way for 2010. Granted I'm working on a 56mpg tank right now despite my 90% freeway commute so it's hard to complain.

I anxiously await the 25th when the reviews come out, hopefully telling us how the 3mpg highway boost translates.

 

How does Toyota get to revise the numbers? Either the EPA numbers are official or they aren't. I can't find any on their website.

 

Nice balance upgrade! +3 City MPG and +3 Highway MPG. +24 hp.

 

The automakers all have the EPA testing parameters. They do the testing in-house well before the official numbers come out.

Due to lack of manpower and for cost reasons the EPA allows each maker to do its own testing in accordance with the the EPA testing cycles. The EPA then verifies and validates each makers testing procedures for that vehicle. If everything is up to snuff the maker's tests and results become official. The EPA can spot check any set of tests it wishes.

 

I can't see how one would be disappointed with the 2010 Prius. I would say the same with any of the Pri.

 

The EPA does not mean much to me. My city driving is full of hills, therefore I get much better mileage on the freeway.

 

From what I've read, the mpg improvements are more drastic when it comes to driving the 2010 in cold weather climates compared to the 2009. I don't think the EPA mpg tests (even the new ones since 2008) factor cold weather.

 

I wonder how the "combined" mpg is calculated.

For the Iconic Prius: 48 City / 45 Highway / 46 Combined - Average is 46.5 MPG

For 2010 Prius: 51 City / 48 Highway / 50 Combined - Average is 49.5 MPG

It does not look like they round the average because for the Iconic they are rounding down while for the 2010 they are rounding up.

 

well the logic of what Toyota did does make sense and is easy to see, but that does not mean it will help everyone. in fact, in my situation where freeway driving is a small part of the driving, the benefit may not be as great.

granted, there is an unknown component in the selectable driving modes that may play a much bigger part than expected and all that should be revealed soon enough, but where i see the big improvement is all the people who are currently getting 45 mpg (which is the largest segment of current Pri owners) and spend most of their time on the freeway at 65 mph.

there is also the faster warmup that will help in town drivers, but in summer, the Pri warms up pretty fast anyway.

as for me, 70% of our driving (can be as high as 100% some weeks) is at 35 mph or less which is the big reason why i am disappointed that WE were not given the option to pay more and get the plug in option.

 

Yes, they do. One of the three new tests is to repeat the FTP 75 test cycle at 20°F (-6.6°C) rather than 68-86°F (20-30°C - backwards step on metrication there!). I'm not sure how this is used to adjust the City estimate, though.

See Fuel Economy Test Schedules and click the 'Detailed Comparison' tab.

 

They use something like 60% city and 40% highway. Also the numbers they get are not 48/45. They round them off when they post on the sticker

 

Relax. The plug-in is still "experimental". It's going to be out either next year or the following year, depending on how well it works, how much they have to charge for it, exactly WHEN the LiION battery is ready, and what the economy is doing.

 

The EPA usually underestimates. Toyota's numbers are more realistic. I see no change here, since +/- 1 mpg is hardly reproducible in the real world. I drive average (no pulse-glide). I get 50-52 mpg warm weather and 44-46 mpg cold weather, mixed driving.Tires about 38/36 psi. Climate varies mileage more than anything else.

 

Toyota will be testing THREE different types of plug-in Li-ion battery with the next generation 2010 Prius. Unlike GM, Toyota will test the battery on the real world road and then pick the best one to mass produce. GM picked their supplier for the Volt just by testing LG Chem and A123 packs in the lab.

 

Hi All,

This change is almost predictable. Cars with nearly the same CdA (Prius III is wider, but with a .01 Cd advantage) move through the air at the same speed over the same distance, they burn up the same amount of energy. So, on the highway they are very close - 46 versus 48. Lower RPM causes less pumps per mile, but its more volume per pump with bigger engine. So, pumping losses are similar. The cylinder sizes, valves are about the same, so that is the same volume going through the same engine internal aero-drag.

Its the city (suburban actually) driving where a bunch more improvement can still be made with the Prius. And they chose not to. That is what is disappointing.

Although I bet the winter fuel economies will be about half way from the present to the summer fuel economies of the III. Simply because they can crank open that heat recovery valve in the winter. So around 15 F high temp days, that means about 58 mpg, instead of 53 mpg for me. Hybrid mode in 3 miles, rather than 10.

 

They are saying 300 rpm lower at 70 mph.

 

If you know what that RPM is we can check the volume per minute between the two configurations.

 

In theory, one might do a quick hack:

(1.5/1.8) * 1NZ_rpm_change
​

So with my NHW11 at 70 mph, I need about 25 hp, which comes in around 2,200 rpm:

2200-1100 ~= 1100 rpm (rpm range above idle, 1,100 rpm)
(1.5/1.8) * 1100 ~= 917 rpm
1100 + 917 = 2,017 rpm (projected 1.8L assumes same idle rpm)
2,200 - 2,017 ~= 200 rpm
​

Add a little more from more efficient, dual valves, electric water pump and reduced cam shaft drag, and you're right in about 300 rpm at 70 mph.

And these improvements were?

Bob Wilson