In cities, use public transport and leave your car in the garage.
For medium- and long-distance trips, public transport is up to 6 times more efficient than the private car.
Check tyre pressures regularly, remove accessories you do not need (e.g. roof rack), do not transport unnecessarily heavy items, use the air conditioning with moderation and do not drive at high speed. That way you will save fuel and gain in safety.
If you have to take your car, apply efficient driving techniques, using high gears as much as possible and the engine turning at low revolutions.
When burying a car, choose a model adapted to your needs and focus on the label stating the CO2 consumption and emissions. At the same level of performance, it is better in economic and energy terms to buy a car in category A or B.
For short trips, walk or go by bicycle; it is more economic in energy terms, less polluting, and healthier.