A car is the second-highest household expense for most Americans, with maintenance and upkeep costing an average of $8,700 per year. One way to curb car costs

is to consume less gas and adopt driving habits that save money. Get started with these four tips.

Map out your errands. Errands have a tendency to take you all across town, but they don't have to. Before you head out, map out your route so you're traveling to the farthest destination and hitting up stops along the way, then traveling home and making other stops en route. This reduces backtracking, which consumes gas and adds extra mileage.

Avoid letting your car idle. If your car were to idle for one hour, it would burn through 1/5 to 7/10 gallon of gas. Put another way, when you are idling, your car gets 0 miles to the gallon. The longer you sit idle, the more gas -- and cash -- you burn. Not only does a few minutes here and there add up over time, idling also pollutes the environment.

Accelerate gently. Sure, it can be fun to race out from a full stop, but hard acceleration consumes more gas than gentle acceleration. Accelerating slowly can also break the cycle of blast and brake that often occurs on roads with timed lights. By cruising slowly, you may avoid the red light and approach the next light just as it turns green.

Coast to traffic stops instead of approaching at full speed. Lift your foot from the gas pedal when going downhill or approaching a traffic stop. You'll keep driving without using gas.

What's your favorite way to curb gas spending?