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How does one go about computing gas mileage in reverse?
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Is this something that comes up often..?
 

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I believe the Prius uses electric for reverse. So whatever it takes to regenerate batteries results in "mpg" for reverse.

But to answer your question, instead of miles/gallon, in reverse it's gallons/mile. If you had a giant SUV you could use gallons per mile.
 

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KTPhil said:
Does the Prius odometer increment while driving in reverse? Buehler? Anyone?
Better yet, does it decrement???? Perhaps when you drive in reverse the car "youthens" like Merlin in the T.H. White version of Arthurian legend.

Gee, that way the poster with the "Maint Req" light could just drive backwards everywhere until the oil got new enough not to need a change!
 

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i do a fair bit of driving in reverse... my parking lot at work is experiencing some huge construction-related interruptions, and to find a good spot you have to drive all the way down that aisle and back out if you can't find one.

most people can't turn around in that tight of a space. i could, but i'm lazy.

this results in a whole lot of reverse driving.

i haven't noticed my daily mileage decreasing since i started doing this :lol:

and since you use electric to back up, it's guaranteed you won't be wasting gas :)
 

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Engage space-time continuim capacitor (important) while in reverse.. and the Prius will ADD gasoline.
PS: If your hear the ICE cut in while in reverse, you may be going too fast. 8)
 

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Really, are you driving that much in reverse? like miles and miles?

it's gotta be a small amount of your overall driving, no?

Spike
 

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Let's see. I go in reverse every day out of my driveway. That's about 9 feet a day. Take that 9 times six days a week and you get 54 feet. Now multiply that times-----well you see where I'm going with this. Perhaps reverse logic?
 

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The odometer will not go backwards in reverse. The speed and distance is done by pulses in correlation to a full rotation of the wheel, rather than a gearing system in mechanical odometers and speedometers. A pulse says the wheel rotated one full rotation, but doesn't say in which direction. That's why the navigation system (and MFD for the graphics) has to know if you are in reverse gear or not.
 

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well, if you go fast enough in reverse you get a positive velocity (positive speed on the spedometer, and not a negative number).

Since velocity = distance/time, and velocity and time are positive values (time isn't going backwards!), the distance must also be positive.

(BTW: if you want to show off the torquiness of the electric motor, find a nice safe area with some good distance, and floor it in reverse! I get chicken in the high teens on the spedometer, but...)
 

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Funny, the other day, I noticed the speedo goes up in reverse; you can then figure out how fast you are going in reverse.

Of course, I just noticed it, since I tend to look backwards/to the side when I reverse the car...
 

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Discussion Starter #16
Prius in reverse

mrv said:
well, if you go fast enough in reverse you get a positive velocity (positive speed on the spedometer, and not a negative number).

Since velocity = distance/time, and velocity and time are positive values (time isn't going backwards!), the distance must also be positive.

(BTW: if you want to show off the torquiness of the electric motor, find a nice safe area with some good distance, and floor it in reverse! I get chicken in the high teens on the spedometer, but...)
I sure hope I take a course in Physics to understand this!! :)
 

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mrv said:
well, if you go fast enough in reverse you get a positive velocity (positive speed on the spedometer, and not a negative number).

Since velocity = distance/time, and velocity and time are positive values (time isn't going backwards!), the distance must also be positive.

(BTW: if you want to show off the torquiness of the electric motor, find a nice safe area with some good distance, and floor it in reverse! I get chicken in the high teens on the spedometer, but...)
Not so. Velocity is a vector, so it has both a magnitude and a direction. If you define forward motion as the positive direction, then reverse would indeed result in a negative velocity. Of course, if you define reverse as the positive direction, then going forward would result in a negative velocity.

Velocity is not distance over time. Velocity is a change in displacement over a change time, and, as it is a vector, displacement can indeed be negative.

Speed is a scalar, so it is always positive, regardless of direction.
 

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Discussion Starter #18
bsoft said:
mrv said:
well, if you go fast enough in reverse you get a positive velocity (positive speed on the spedometer, and not a negative number).

Since velocity = distance/time, and velocity and time are positive values (time isn't going backwards!), the distance must also be positive.

(BTW: if you want to show off the torquiness of the electric motor, find a nice safe area with some good distance, and floor it in reverse! I get chicken in the high teens on the spedometer, but...)
Not so. Velocity is a vector, so it has both a magnitude and a direction. If you define forward motion as the positive direction, then reverse would indeed result in a negative velocity. Of course, if you define reverse as the positive direction, then going forward would result in a negative velocity.

Velocity is not distance over time. Velocity is a change in displacement over a change time, and, as it is a vector, displacement can indeed be negative.

Speed is a scalar, so it is always positive, regardless of direction.
Can you translate this into "English" for us "knotheads"? :oops:
 

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Reminds me of some of my science classes. I could memorize and feed back the definitions/terminology, but not truly understand their application. I remember vectors, but scalar? That's a new one.
 

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Speed is what your speedometer shows. It doesn't care if you're going backward.

Velocity is what your speedometer shows along with what your compass shows. If you're going backward you need to use the opposite compass reading.
 
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