Driving A Hybrid

[skruse]

The Rocky Mountain Institute (RMI) is an entrepreneurial nonprofit organization that fosters the efficient and restorative use of natural, human and other capital to make the world secure, just, prosperous and life sustaining. RMI does this by inspiring (modeling what it teaches) business, civil society and government to design integrative solutions that create true wealth.

RMI leased a Toyota Prius in March 2005 to be the new "company car." RMI encourages and prefers use of the "RMI blue" Prius instead of a staff member's own vehicle. RMI tracks kilometers driven vs. Liters of fuel consumed for each driver to understand how kmpL (mpg) depends on behavior when compared to other factors, notably weather (the regenerative storage battery does not work well at low temperatures and the tires are not as efficient on snowy or slushy as on dry roads).

RMI recommends "pulse driving" which differs two ways from normal driving habits:

1. When you see that you will need to slow or stop up ahead, start braking gently and as early as possible so you recover the most braking energy into the battery for later use. Prius recovers 62-66 percent of braking energy in the regenerative mode, but if you brake too late, hence too hard, the mechanical brakes override and then simply turn the kinetic energy into useless heat.

2. Contrary to what we were all taught in high school driver's education, when you are accelerating up to cruising speed, do so briskly. the engine is most efficient at high speed and torque, so you will use less fuel accelerating aggressively for a short time than gently for a long time.

RMI notes that many reviewers test hybrids driven in the same way as nonhybrids, then gripe that hybrids fall short of their rated efficiency by more than nonhybrids do. This is incorrect; properly driven hybrids can actually match their EPA rated fuel efficiency more closely than nonhybrids. Toyota's US Executive Engineer, Dave Hermance, gets 53-55 mpg in his 55 mpg-rated Prius.

Consumer Reports is a major source of hybrid fuel efficiency confusion, having repeatedly refused to print a correction explaining that CR's standardized test procedure disproportionally reduces the fuel economy of hybrids CR tests. CR also calculates combined city-highway fuel economy differently than EPA and automakers do.

RMI advises that consistent with attentive driving, you will find it very instructive, when driving a hybrid, to keep an eye onthe real-time kmpL (mpg) MFD display and use the feedback to improve your driving habits for best fuel economy.

RMI's work is independent, nonadvesarial and transideological, with a strong emphasis on market-based solutions. We are fortunate to have international RMI modeling what it teaches and working with governments around the world.

[plusaf]

always reminds me of one of the first responses to the ORIGINAL EPA mileage pronouncements:

the epa was tasked with making sure that auto engines didn't emit more pollutants than the laws allowed for the respective cars.

apparently, someone noticed that, during the process of measuring the emitted gases from during the tests, they could calculate "gas mileage" from the mass of chemicals emitted during the distance traveled.

one wag called this the equivalent of measuring rainfall by weighing the earth before and after a big storm....

they apparently never considered the "measure the mileage out divided by the gasoline in" until many years later.

and then, they had to design a "typical driving cycle" which, by its very nature, can never reflect what virtually any driver can expect, since this "typical" is the result of averaging a bunch of individual "cycles" but essentially nobody drives "the typical cycle"....

such silliness...

for some years, i've thought that the EPA could get out of this rut by just using an "EPA versus Reality" fudge factor, of maybe 80% or so, and admit that the average driver will get about 80% of the EPA ratings, and just have done with it....

ah, too simple of a solution...