my car

Vehicles are least efficient and most polluting at the start of trips and on short trips.

One reason for this is that catalytic converters (which reduce air pollution emissions) do not operate properly until they have warmed up. You can reduce the number of cold starts you make by combining a number of trips into one.

Stop/start driving is much less efficient and more polluting than driving at a constant speed. In comparison, free-flowing driving, such as uncongested country or freeway travel, uses the least amount of fuel per kilometre. If possible, organise trips in advance to avoid congested areas and peak-hour traffic.

The best way of reducing emissions and fuel consumption is to reduce the amount of driving you do. For short trips, consider walking or cycling. For longer trips, you may prefer to take public transport or share a lift. Or you could use the phone instead of making a trip.