This year I got to look closer at the highway data and wanted to share some observations:

• current ICE at high power - the brake specific fuel consumption begins to fall off above 2,600; gets a steeper decline at 3,150; and really heads the wrong way above 3,900 rpm.
• transaxle efficiency - is not too bad with the NHW20 but the NHW11 has a very steep decline above 65 mph. This appears to be due to a control law that tries to limit MG1 rpm.
• loss of 'energy recycle' mode at high power - instead of taking some energy from MG2 and feeding it back to MG1 in a type of 'over drive,' at high power, the transaxle seems to flit over to the basic mode used for acceleration with higher engine rpm.
• transaxle loss - looks to be about 2.5%. This is not a bad number but would be better if there were a mechanical 'lock up' at high speeds.
• differential immersion - right now the differential gear appears to be immersed in the transaxle oil. There are alternate architectures, especially those that run non-immersion, that could further lower transaxle losses.
• tire alignment - could be better.

Bob Wilson

 

The HSD system, and the nearly identical system used by Ford is very versatile. It can be optimized for city cycles (Prius), or very well balanced for city/highway cycles (TCH, FEH), or optimized for performance (Lexus GS hybrid). However, the Prius is pretty well balanced, with only slight advantage given to the city cycle.

What other vehicles of similar size and weight, say within 10%, does better than the Prius on the highway (or even gets within 10%)? You say there are quite a few. Please list them for us. I'm not saying you are wrong, but I'd like to know which comparable vehicles compare well to the Prius for highway mileage. Note that I am asking for comparable vehicles with comparable highway milage, and not just those that put the Prius at a "serious handicap".

If you are only referring to diesels, then also figure in the 44% higher cost of diesel fuel (today's US average is $1.613 for gas vs. $2.327 for diesel per US Dept of Energy). A diesel would have to get 65 MPG to equal the cost per mile of the Prius 45 MPG highway.

-- Alan

 

When I bought my Prius (Feb., '06 - all the planets and stars in alignment as I got the full Fed Tax Credit and California's car pool sticker - and paid sticker price) there was nothing which got comparable mpg, highway, byway, Long Beach/Orange Cnty traffic. NOTHING! I looked at the Honda and knew immediately we were not going to hit it off because I could not chuck a full size bike into its trunk.

As it happens, I must have the only Prius station wagon in the world.

I can't say anything about the engineering aspect of the Prius, but we know that much of what we get out of it is the result of one's ability to maximize it's characteristics. So, can't say if its me or the Prius, or whatever. Again - I get my best mileage on the highway.

I'll be in Mesa in March on my way to Tucson. Don't think, however I'll be looking at another Prius. I figure mine is good for another 200,000+ miles.