Fuel expenses account for a significant share of fleet costs, but trucking lines don't always know where to look for cost-saving opportunities.

Edmond, Okla.-based GPS tracking system maker US Fleet Tracking has some ideas on that. It contends that lax driver practices are a prime cause of wasted fuel and that companies can identify and address the troublespots through the use of GPS tracking devices.

To illustrate how GPS monitoring can help, US Fleet Tracking offers the following tips for cutting fuel consumption through the use of GPS tracking:

First, take advantage of the GPS device's route planning feature. Though it may be unintentional, drivers often fail to take the shortest route. Maybe the long way around is the only route they know, or perhaps they're relying on outdated phone apps or navigation devices and end up getting lost and wasting mileage in the process. By tapping into the route planning feature of a GPS device, a dispatcher can determine the shortest and quickest routes and give drivers turn-by-turn directions to pickup and delivery sites.

Second, keep an eye on idling times. When temperatures drop, drivers may keep the engine running longer than necessary in an attempt to warm up the cab. But every second of idling adds up, wasting fuel and degrading the engine, the company says. GPS tracking reports and alerts can help managers curb this wasteful habit.

Third, watch that speedometer. While it may be common practice to cruise at five to 10 miles per hour over the speed limit, speeding burns extra fuel and stresses the engine. With GPS tracking data, dispatchers can record data, generate reports, and even send drivers "slow down" alerts via e-mail or text message.