You may not have a more fuel-efficient car yet, but there are still ways for you to save money while driving.
With windows or air conditioner open?
It really depends on the situation. Drive with the windows open if the car has been parked under the sun for hours. You can open the air conditioner once the car has already cooled down. The bottom line, still, is that less power means less fuel.
Regular fuel or premium fuel?
If your car goes well with regular fuel, there is no more need to run it with something higher in octane. On the other hand, going for premium fuel is best if you have a supercharger or a turbocharger.
Light acceleration or heavy acceleration?
Considering light acceleration will surely not hurt you. Aside from saving money, you will also be less prone to meet accident (knock on the wood). By and large, light acceleration saves fuel.