OT: Hybrid cars

[Oleg Goldshmidt]

guy keren <guy.choo.keren at gmail.com> writes:

> "watching the numbers occasionally" is not a proper experiment. you
> need to reset the computer before you start the "drive under test",
> and check the value after - and the length should be enough to even
> out the fluctuations.

I don't know what your car shows you. Mine directly shows the fuel
consumption at the moment (that jumps around) and a running average over
some period of time that is updated every few seconds. I don't remember
what the averaging period is exactly, but if you drive at a steady speed
for a while (I have cruise control, too) you will get a pretty stable
number on the screen.

These are two different screens on the dashboard that I can switch
between with a button on the steering wheel. The computer screen is
right next to the speedometer, so I can watch the speed (even without
cruise control) and fuel consumption simultaneously.  In principle, I
think there is another screen that reports your running average speed,
but I don't think I used it for this purpose.

I don't know what you mean by "resetting" the computer. I assume you
reset the "trip distance" counter. I don't even need it to watch the
fuel consumption numbers.

It sounds like you took a trip with a full tank, guesstimated your
average velocity, and topped the tank again to see how much fuel you
spent. If I misread, sorry. If this is roughly what you did, then I am
sorry to say I am not particularly impressed with the methodology (I
realize this is the only thing you may be able to do - no offence meant
at all - it is better than nothing). It cannot possibly be close in
precision or reliability to direct observation of km/l or l/km.

I hope the above gives you a good idea how I know.  This is the least
"theoretical" approach mentioned so far. All my "occasional
observations" disclaimers mean that I didn't obsessively do it over
dozens of trips, write down the numbers, run F-tests or whatever...

> one thing to note - the car uses more then just fuel to recharge the
> battery. every time i leave the accelerator (e.g. when coming to a
> traffic light, or due to getting too close to a car in front of me) - 
> the battery is being recharged. 

I made a note of it in my very first post.

-- 
Oleg Goldshmidt | pub at goldshmidt.org