Smaller engines can be made to act like bigger engines as seen with direct fuel injection or turbo chargers. Or larger engines can act like smaller engines as seen with cylinder deactivation.
Fuel efficiency is generally gained in one of two ways, said Brett Smith, co-director of manufacturing, engineering and technology at the Center for Automotive Research in Ann Arbor, Mich. Smaller engines can be made to act like bigger engines as seen with direct fuel injection or turbo chargers. Or larger engines can act like smaller engines as seen with cylinder deactivation.
The Chevrolet Caprice PPV uses Active Fuel Management, while the 5.7L Dodge Charger Pursuit uses Fuel Saver Technology, both alternative names for cylinder deactivation. These technologies can give up to a 10 percent increase in fuel economy, Smith said. The current V8 engines with cylinder deactivation are the cheapest option for police, Smith said, both in initial cost and maintenance.
Ford’s twin turbo Police Interceptor and the 2012 V6 Caprice use direct fuel injection to make gains in horsepower and efficiency. This technology is more expensive to build and maintain, but Smith said it’s becoming more popular than cylinder deactivation because it creates more efficiencies.
Carbon Motors’ E7 runs on a turbocharged diesel engine, which the company promises will give at least a 40 percent improvement in fuel economy over the current industry average. “If you’re going to be driving a lot, a diesel engine is a great thing,” he said. “It’s a wonderful powertrain for a cop car.” Diesel engines are more expensive than gasoline engines. And while the increased fuel efficiency of diesel would allow law enforcement agencies to get their money back after a couple years, it’s possible they may not want to wait to get those cost savings, he added.
Ford, Chevrolet and Dodge all offer cars compatible with E85 “flex fuel.” E85 is an alternative fuel made from 85 percent ethanol; it’s slightly more expensive than standard gasoline and less efficient than standard gasoline and diesel, Smith said. “Corn ethanol,” he said, “is not a long-term viable fuel.”
Instead Smith would prefer to see stop-start systems, a technology used widely in Europe that shuts down the engine during idle times and restarts it when the driver wants to move again. The technology is well suited for police vehicle usage patterns.