How are you making so many MPGs!?!

[Rybold]

Bob, I would love to do a test, but I have no way of measuring the actual fuel consumption (I have a Corolla, not a Prius. I will have a Prius within the the next 12 months, but not yet).

Wfolta, I attempted the 30-20, 20-10, and 10-0 today, however I was unsuccessful because I could not find a road long enough. I found a road with very light traffic and a low speed limit that appeared flat, but at 30mph, 20mph, or 10mph, my car just kept rolling and rolling and rolling until I ran out of road. (car was in neutral) That was in one direction. Going in the opposite direction, I was able to get a number for the 30-20, but for the 20-10 and 10-0 I ran out of road in the opposite direction as well. The approximate length of the road was about one mile. Unfortunately, there are not many roads in Orange County that are near flat for more than a mile (and where you won't get rear-ended by an agressive driver).
Results (including yesterday): In neutral, it took 15sec to decel from 70mph to 60, 30sec to decel from 60 to 50, and then to decel from 30-20 took over one minute, and 20-10 and 10-0, it kept "going and going" until I ran out of road (which was limited to one mile).

Conclusion (coupled with results I posted above): Wind resistance at 70mph and 50mph is significant, it is much less a factor at speeds below 50mph, it is very slight at 30mph, and at 20mph and below, it is undetectable in the absence of advanced equipment.

edit: Bob, I noticed that all of the data points on your graph were performed under 45mph.
edit2: Now that I think of it, I could easily have performed the 50-40 and 40-30 on that road. I'll have to do that tomorrow. Yes, I'm sure many people have already done this and posted very precise graphs, but I'm having fun performing my own experiment.

[wfolta]

Wow, lots of experimenting and graphs going on here!

Bad news is I may be without my Prius for a while -- starting: not sure when. The Prius has a much smaller turning radius than I'm used to and... I managed to turn into a concrete post in the parking garage. Sigh. Not sure when or for how long it will be in the body shop.

Good news is my mileage continues to climb as I'm trying new things and the car is braking in. On this tank, with a mixture of highway, city, and traffic jams, I'm at about 55 MPG, with a personal record of 57 MPG for a while. Seems to me that I should be able to achieve 60 MPG overall in another month or so.

[Argyle]

Originally Posted by wfolta

Wow, lots of experimenting and graphs going on here!

Bad news is I may be without my Prius for a while -- starting: not sure when. The Prius has a much smaller turning radius than I'm used to and... I managed to turn into a concrete post in the parking garage. Sigh. Not sure when or for how long it will be in the body shop.

.

Brothers and Sisters, can I get a "D'oh!!" from the congregation?

Sorry to hear that. Hope the damage was not excessive. Best of luck.

[DaveinOlyWA]

the Pri is designed to be ultra efficient which means reducing drag as much as possible, the beltless design, etc. all play a part.

so to coast from a stop even at 10 mph will take a while. i commented on this waaaay back in 2004 that my Pri seemed to coast in neutral farther and faster than any other car i had owned.

[WPWoodJr]

Originally Posted by wfolta

I'll try it today to get actual numbers, but if I accelerate at 20 MPG for 8 seconds, then glide at 100 MPG for 8 seconds, I'm achieving something like 60 MPG. (It's more complex than that, I think, but.)

It is more complicated than that. In your example the total MPG is only 33. I explained this here:
http://ffh.squarespace.com/blog/2009...and-glide.html

[OZ132]

Add to fuel, and motor oil...