While forthcoming electric-drive vehicles capture automotive headlines, manufacturers are making more subtle technological improvements to their current offerings of hybrids and conventional vehicles. Toyota’s 2010 Prius, the most efficient gasoline-powered vehicle and number two on ACEEE’s “Greenest” list, shows a 3-mile-per gallon increase in fuel economy, to 51 city / 48 highway. Toyota attributes the gains to an increase in engine size — which allows the engine to operate at lower rpm on the highway, together with a new exhaust gas recirculation system, an electric water pump, a lower coefficient of drag, and lightweighting of several parts, though overall vehicle weight has increased in the bargain. The new Prius also features LED low-beams and taillights, a more efficient A/C system, and solar panels on the optional moon roof. New hybrid offerings — the Honda Insight and the Ford Fusion/Mercury Milan — broke into the year’s top twelve, and several more are slated for arrival later in the year.
The 2010 Ford Fusion appears not only in hybrid form but also as the Fusion S, a conventional model achieving a 17 percent boost in fuel economy over last year’s 4-cylinder automatic using variable cam timing and a six-speed transmission. Ford also added to its roster of vehicles with EcoBoost, an engine package combining turbocharging with direct injection. But while the technology has been touted as offering fuel economy gains up to 20 percent, this year’s Flex and Taurus models use Ecoboost to achieve V8 performance with a V6 engine and leave fuel economy unchanged. The Lincoln MKS with Ecoboost does gain two miles per gallon on the highway and one in the city, however. Other Ford fuel-saving tweaks include a Lincoln MKT featuring a liftgate lightened 40 percent through the use of magnesium and aluminum instead of steel, and electric power steering to replace a hydraulic pump.
More generally, the use of engine refinements such as variable-valve timing continues to rise, and lightweight materials, better aerodynamics, and improved transmissions are all experiencing flurries of activity that demonstrate the large potential still remaining to reduce the fuel consumption of conventional vehicles without compromise in consumer appeal. Yet, in the big picture, these new technologies are not yet moving the needle perceptibly on environmental performance. Indeed, the average Green Score stayed level this year at 32.