Yes, it will decrease fuel mileage slightly. Reason being is that on all modern vehicles when the defroster is run the A/C compressor is also running. The compressor is driven by the engine and this extra load on the engine will require slightly more fuel. The benefit provided by the defroster far outweighs the slightly more fuel you will use.
It is the car running too rich. or the car is using more gas than air.
Only if your defroster uses the A/C, otherwise heater will not effect gas mileage. The heater uses the waste heat from coolant used to cool the engine, so has no extra load on the engine. The heat was going to waste anyway. You are just diverting it into the car instead of outside.
More gas is used when you accelerate, that's why using cruise control is a gas saver, it keeps your vehicle at a constant speed.
Using the air conditioner never saves fuel. But if you are going to use the air conditioner it is better at highway speeds than having the windows rolled down. In the city is better to turn the AC all and open the windows.
because the car burns gas to move
You can save about 30% of gas using a hybrid car. Read more at # www.howstuffworks.com › Auto › Car Models › Hybrid Cars
No
You have to pay for gas and all the tune-ups on the car. Using the car sends emissions into the air which causes global warming. You could get more exercise if you walked instead of used a car.
Yes, By using more battery power and less gas to run the car.
Cars will use more gas idling than starting the car.
Raise the rear of the car using and use jackstands or car ramps (More effective and secure). It is located behind the gas tank.