Generally a burning plastic smell in a car indicates wiring getting hot enough to melt the insulation. This is something that should be looked at immediately to prevent a fire.
Defrost uses the a/c, if it doesn't smell the same with a/c only on. The smell is coming from the blower motor. Bmw's for example have a problem where the blower blade contacts the plastic housing and causes it to rub/melt.
The new car smell is caused by the combination of materials found in new automobiles. The adhesives and sealers used when a car is first manufactured release volatile organic compounds in the air afterward, leading to the smell.
because your car burns alot of petrol after driving several miles
Because it's hot, it burns gasoline, and there are plastic-coated wires.
If the car is a manual and you are riding or slipping the clutch it could be that. Otherwise if you have been real hard on the brakes lately they can create quite a smell aswell.
Several thing scan cause a burning smell from a car A/C. One cause can be that the compressor is burning up. Another possibility is a wiring shortage.
look to see if exhaust is touching plastic somewhere. (get under car) engine probly isn't the cause.
It could have a blown gasket which causes that smell. And there could be something loose in the interior of the air conditioner.
Every Car Product has it's own smell. Overtime there is a possibility that the smell will remain on/in the car. But it will depend on the product and the strength of it's smell.
when changing the oil sometimes oil can be spilled on the engine block. as your engine heats up it causes this smell. it is completely normal
It makes your car smell somewhat new, but be careful as too much will make it smell like a cab, unless of course you want to go for the cab smell.