Reverse & mpg - GreenHybrid

sweetbeet · #1 (**permalink**) 06-24-2005, 05:51 AM

OK, here's one that's been bothering me in my spare brain cycles. My FEH (and probably most of the other hybrids out there) has an "average fuel economy" display. So how would it calculate mileage if I drove in reverse for a substantial period of time? Would the mileage become negative? Would it use absolute value of distance travelled, without regard for direction, to calculate - so that if I travelled 100 miles in reverse on two gallons, it would show "50 mpg"? Would it simply disregard the miles travelled in reverse? Does anyone know how it actually works, or have any opinion as to how it SHOULD work?

Also, I have never looked, but if you go fast in reverse does the speedometer stay pegged at zero or does it go up to reflect the actual speed at which the car is travelling? (I think I'll try that next time I'm in a big, empty parking lot.)

C.

hawkGT647 · #2 (**permalink**) 06-24-2005, 06:24 AM

I do know on the Insight, the speedometer will read out a positive number for speed in reverse. This is a digital readout. I've had it up to 12 miles per hour going backwards down a backroad.

But I don't know how it would affect the fuel calculation. Reverse is geared so low in most vehicles, I would guess that overall you would give up some MPG's.

Things that make you go "hmmm?"

Regards,

zadscmc · #3 (**permalink**) 06-24-2005, 06:54 AM

I am told that a mile in reverse is the equivelent to a mile in forward. The absolute value of the distance traveled is added to the odometer and mpg.

solecondad · #4 (**permalink**) 06-24-2005, 07:06 AM

I think zadscmc has it right. My Saturn adds miles in reverse to the odo, altho it doesn't have a mpg meter to check on that side of the question.

Schwa · #5 (**permalink**) 06-24-2005, 01:07 PM

In the Prius (and probably all the others that have the Toyota system) there's no reverse "gear", the electric motor just spins backwards, so I wonder what kind of mileage one could achieve in reverse since it's strictly electric? I would also assume the gear ratios are adjusted in reverse, the same as going forward, so probably not like going reverse in a conventional car with low, single reverse gear.

I like to test out the Prius' electric motor acceleration power in reverse, it's actually pretty powerful. Makes me wish it would do that much work going forward, and I suppose it could if it was a Prius II with EV mode button.