Refrain from braking at all times. Just step off the gas and the vehicle will eventually stop from the friction counteracting the momentum. It is often cheaper to pay for the damage to the vehicle in front of you, unless you’re a cheapskate.
If you’re too lazy to walk to the next store after you’ve parked, consider getting into your car with the door ajar, and push, push, push.
Always be friendly with traffic police, so they’ll allow you to run red lights and save energy.
Don’t use your car stereo or airconditioner. If you open your windows, you can just listen to the blaring music from the car beside you. Of course, bring a fan.