You can improve your fuel efficiency if your refuel your vehicle during the evening hours to reduce the amount of environmental pollution created. You can also combine errands and plan out the shortest route possible. The heaviest car emissions occur during the first two miles that a car is driven (while the engine is still cold). Whenever possible, walk or ride a bike to your destination. It is also environmentally-advisable to choose a home within walking or biking distance of work and stores.