More gas compared to what, not using the HID's?

Usually you don't have a choice, but yes it does draw more current from the alternator and does use, not really waste, more gas. To what extent is probably almost impossible to calculate though I'd assume it's very small. I know on my motorcycle with HID, even with a tiny alternator and 954cc vs 2000cc engine, the gas mileage between using the HID and not using it isn't noticeable.

 

[QUOTE=sahtt,Nov 5 2007, 02:25 PM] More gas compared to what, not using the HID's?

Usually you don't have a choice, but yes it does draw more current from the alternator and does use, not really waste, more gas.

 

I'm in the camp that says a colder (& more dense) charge is going to require more gas to run at the correct air/fuel ratio - to what extent the ECU avoids this, I have no idea. But it is certainly possible that your car would get worse mileage (but more power) in the extreme cold.

I know that I get 2-3 mpg WORSE in the winter in MN, but that is probably a combination of winter fuels, cold temps, and sticky-as-hell squishy snow tires. Of course, I'm driving slower too, which probably pushes the mpg up.

 

I actually thought cars get better fuel economy when it is hot... Two reasons:

1) If you look at dynos, they DO get more power in the cold in the dyno because it sucks in cold air (more air molecules). most air intake tests are done early in the day where it is cold, or some people may even "cheat" by putting a bag of ice over the intake.

BUT, racecars never race when it is cold (except rally). Good racetracks are built on deserts, because the grip is better. Even though cars lose power when it is hot, fuel economy and speed is better because more of the power is delivered to move the car.

2) Also, in the cold, more air means more gas is burned, since the car tries to stay at the stoichiometric point. Think turbochargers.