Gas Mileage Calculation

[LCB]

I was just curious about the calculation of when I am sitting at a stop light for 5 minutes, my engine is off completely, does this calcluate in extra mileage?

I would guess not, but shouldn't it be calculated somewhere? I mean other cars sitting around me are idling still burning up the gas, especially the automatic cars, while I am burning ZERO fuel.

So I am really thinking that if you are getting around 27-28 miles per gallon, then that really equals a 30-31 miles per gallon for a typical gasoline car.

[RX400h]

This is the beauty of a hybrid - stopping or puttering along in a traffic jam means that no fuel is being consumed. This is why the EPA City estimate is 31 MPG - plenty of engine shutdowns. I'm not sure how the RX computer calculates fuel usage, but I have checked number of gallons used vs number of miles driven and it agrees almost perfectly with the MPG readout (25 MPG).

[markatty]

I was just curious about the calculation of when I am sitting at a stop light for 5 minutes, my engine is off completely, does this calcluate in extra mileage? 

I would guess not, but shouldn't it be calculated somewhere?  I mean other cars sitting around me are idling still burning up the gas, especially the automatic cars, while I am burning ZERO fuel. 

So I am really thinking that if you are getting around 27-28 miles per gallon, then that really equals a 30-31 miles per gallon for a typical gasoline car.

←

When you are stopped at a light with the engine off you are getting 0 miles and using 0 gallons of gas, so you could look at this period as not effecting your miles/gallon at all. Its the same as when you car is in the garage at night. However, when comparing it to an ICE (which I finally figured out stands for internal combustion engine) there is a difference. The ICE is idling at the stop light while it obviously isn't in the garage at night, so a normal car loses mpg stopped while the RX-400 doesn't. Unfortunately mpg is mpg so if you are getting 27 mpg and the little Volkswagen is getting 27 mpg including the time that it is idling you have the same mileage as the VW, but you have a better experience while getting the same mpg. :D

[gtistylee]

just because your vehicle is idling it does not necessarily mean your ice is not running. did you forget that the ice will turn on to re-charge the electric motor, even at idle?

[RolandB]

I was just curious about the calculation of when I am sitting at a stop light for 5 minutes, my engine is off completely, does this calcluate in extra mileage? 

I would guess not, but shouldn't it be calculated somewhere?  I mean other cars sitting around me are idling still burning up the gas, especially the automatic cars, while I am burning ZERO fuel. 

So I am really thinking that if you are getting around 27-28 miles per gallon, then that really equals a 30-31 miles per gallon for a typical gasoline car.

←

It works the same way as your bank account; while you're sitting there not using gasoline, you're not spending money and therefore are getting richer by the minute ! Aghhhhh... couldn't resist!

Roland

[LCB]

just because your vehicle is idling it does not necessarily mean your ice is not running. did you forget that the ice will turn on to re-charge the electric motor, even at idle?

←

Yes, but you can tell when the motor is running. 95% of the time while sitting at a stop light, the ICE is turned completely off. You have to sit for a few minutes before it will need to turn on if you have been driving awhile and battery is charged.

[jashev]

just because your vehicle is idling it does not necessarily mean your ice is not running. did you forget that the ice will turn on to re-charge the electric motor, even at idle?

←

I have rarely seen the ICE come on just to charge the battery at a stop light. Generally the coasting and braking before the light has already given the battery an adequate charge. Your ICE however, will ALWAYS run whenever the A/C compressor is operating.

[katzjamr]

Since the AC runs off the battery, if it is well charged it will run for a period without ICE.

[speedyg]

I think there is calculation going on even when you are stopped at a light. I've only had to do this once, so am not 100% sure, but one day when it was really hot out I had to wait in the car with the A/C on. The gas engine quickly shut off because it wasn't needed, but my primary battery gradually got used up, at which point the gas engine started up again and I'm pretty sure the MPG reading did drop (all this time I was parked) because I was using gas.