Ford says its hybrid gas/electric Escape SUV that goes on sale in 2003 will be followed by a hybrid gas/electric Explorer at an unnamed date.

The Escape HEV will feature an electric drivetrain powered by nickel-metal-hydride batteries combined with a fuel-efficient 4-cylinder gas engine. Escape HEV will deliver 40 m.p.g. in the city and 31 m.p.g. on the highway, Ford said.

The reason for the higher city mileage is that batteries will start the vehicle and get it up to cruising speed, when the gas engine will take over.

The Explorer HEV will be equipped with a V-6 that can turn itself off at stoplights and restart as soon as the driver lifts off the brake pedal, with technology similar to that in the Honda Insight.

The technology that allows this start/stop feature is known as an integrated starter-generator (ISG). Run by a 42-volt battery, the ISG system also assists the engine at startup and in hard acceleration, providing short bursts of added electric power.

The Escape and Explorer HEVs will recharge their batteries while the vehicles are driven by regenerative braking, in which the energy created in braking is captured and directed back into the batteries.

Ford scientists also are experimenting with a black gooey substance that can change viscosity on command.

Ford's goo, known as magnetorhelogical material, can behave as a free-flowing liquid or a paste-like solid, switching properties when a magnetic field is applied.

Ford is trying to use the substance to subdue the clicking that occurs when air conditioning clutches engage and disengage. When the clutch disengages, the material turns to a fluid to let the clutch slip out of contact.

This soft engaging and disengaging of the clutch also makes power surges from the engine less noticeable, a condition typically felt in vehicles with small-displacement engines.