Does turing the heater on in ur car increase ur fuel milage, decrease it, or neither?

Question

i know turning on the A/C decreases it

but the heater works by funneling heat FROM the engine

would this make for better fuel milage?

or is it still worse

also

is having the vents on (no A/c) better or worse than no vents

Answer 1

In short, the answer is it makes no difference to both counts.

The heater of the car functions by allowing a portion of the engine coolant to flow through the heater core inside the car (looks similar to the radiator). Older cars allowed the coolant to flow to generate internal heating, late model cars the heater core is always on, but air is only drawn through it when you select heat.

Just a point of interest - in late model cars it is usually more fuel efficient to use the A/C instead of winding down the windows, which can cause wind drag on the car increasing fuel consumption.

Answer 2

Any influence on milage from the heater is negligible. The A/C lowers milage, but having the windows open reduces milage more due to air resistance and drag. So, in general, using the A/C and keeping the windows closed yields the better milage.

Answer 3

Yes, having any sort of extra circuit on has a great pull on the engine which makes it have to use more fuel to keep up a good pace. If you want to save gas, don't use the A/C or heater. That can be hard sometimes though.

Answer 4

Turning the heater on and off has no relationship to fuel mileage on most cars. You are simply using the heat generated by the engine's coolant and directing it to the interior of the car. As far as comparing it to the AC, the AC uses a compressor to move the freon in the system. This requires a slight amount of power from the engine and will result in an insignificant drop in mileage. The vents are simply allowing outside air into the car and the only power consumption occurs when the fan is on. Again this is electrical power and does not really affect the engine.

Driving habits and poor maintenance are the biggest areas where mileage can be improved. You can change your fuel consumption greatly by driving sanely.

Answer 5

Using the A/C makes very little difference in gas consumption.  The compressor is still turning even when off, it's free wheeling.  The drag on the engine when it clicks on is minimal, it's like trying to make your car lighter by emptying the ash trays.

The heater only uses the hot coolant that is already present to warm the interior by sending it through a heat exchanger.  I suppose you could argue that the fan that moves the air causes a load on the electrical and makes the alternator work harder, but again it would be too small to even measure.

The vents only open your inside vents to outside air, often times through some sort of cabin filter to keep out allergens, and would have no effect of mileage.

If you are looking to improve mileage, keep your tires inflated to the proper level, use cruise when possible, and avoid jack rabbit starts and aggressive stopping.  Keep your filters changed and clean, and your engine well tuned.