ATLANTA — With a fleet of 88,000 vehicles, UPS has figured out some simple, yet effective, ways to save fuel: Don’t leave the engine idling, accelerate smoothly, drive the speed limit, and keep the engine tuned. In addition, UPS advises drivers to plan and consolidate trips and consider buying a new hybrid vehicle. The company, itself, has spent $15 million on alternative fuel vehicles. UPS has long required its drivers to turn off their idling vehicles during even brief drop-offs and deliveries. On Saturday deliveries — when the company doesn’t need all its trucks — it runs only the newest, most fuel-efficient fleet vehicles. UPS is also now rolling out a $600 million system that automates how it handles and plans for package delivery, down to the minute. The new system allows the company to pre-plan the exact order for delivering packages by a given driver. The ultimate goal of the system: to minimize inef-ficient detours, reduce instances of misdirected packages, and reduce 100 million miles driven an-nually. Once the system is fully in place in 2007, UPS predicts that it will save nearly 14 million gallons a year in fuel. UPS spent more than $1.4 billion last year on fuel, which was nearly 4 percent of its revenue. The company operates one of the nation’s biggest trucking fleets, runs the ninth-largest U.S. airline, and delivers more than 14 million packages a day. The average age of trucks in its fleet is about 12 years. The company continues to push for fuel savings, said Robert Hall, the environmental manager for UPS’ automotive fleet. “We’ve always been focused on fuel efficiency because it’s such a large expense in our business,” he said, adding that UPS stresses fuel-saving basics to drivers. UPS also revamped its vehicle maintenance program in recent years to customize scheduled work for each truck, based on its type, age, and use. UPS has tested natural gas vehicles in its fleet, and may test electric vehicles; however, the costs of implementing hybrid vehicles is a concern, according to Hall.