The hybrid drivetrain couples the inline four-cylinder engine, CVT and traction motor into a compact package up front.
Except for the prominent "Hybrid" badges, the driver's side forced-air vent for the battery is the only clue that this is no ordinary Escape SUV.
The Sanyo-sourced battery pack is filled with 250 D-cell NiMH batteries wired in series and producing 330 volts. The metallic cassette slips beneath the rear carpet and acts as the load floor. It steals very little room and is thermally protected for the extremes of heat and cold it's likely to ever see.
Despite all of the talk about how Ford's full hybrid system is licensed from Toyota, Ford insists its design draws on fewer than 30 of the 370 patents Toyota has on its hybrid drive. And those licensing agreements were made to make sure no toes were stepped on–and no ugly headlines about how Ford "stole" Toyota technology were generated. Says one Ford insider involved in the project: "It was easier to pay to have access to a few of the Toyota patents than to have to defend ourselves in the media–or in court." Oddly, this has caused some critics to claim that Ford's system is a Toyota design, despite Ford having developed much of its hybrid drive in-house. It's all very confusing, and has fed a small industry focused on determining who is leading this race and who is following. It's all very silly.
Because beyond the tortured logic and schoolyard bragging rights it's apparent that being first or third out of the gate isn't as important as being in the race. And the Escape Hybrid is very much in the race, even if its specifications seem familiar. The small SUV runs an Atkinson-cycle variant of the 2.3-liter Duratec 23 four-cylinder engine, which increases efficiency by nearly 4% compared to the standard Otto-cycle Duratec 23 in the base 2005 Escape. An Atkinson-cycle engine mixes a portion of the unburned air-fuel mixture with the incoming charge by closing the intake valve well after the piston begins its compression stroke. Unfortunately, though this lengthens the power stroke relative to the effective intake stroke and extracts more energy from the fuel, it also lessens the amount of torque the engine produces (129 lb-ft @ 4,500 rpm for the hybrid vs. 152 lb-ft @ 4,250 for the base vehicle) which is clearly felt at low speeds. Gearing the hybrid's standard CVT transmission so that it overcomes this performance deficit would adversely affect the gear spread, and reduce or eliminate potential fuel economy gains at higher cruising speeds.
Ford has packaged a 70-kW (approximately 94-hp) permanent-magnet electric traction motor, 133-hp gasoline engine and CVT in almost the same space as the conventional four-cylinder drivetrain. The Escape Hybrid can draw on the instant torque of the motor to get things rolling; the vehicle runs only on the electric motor during part-throttle acceleration up to speeds of 25 mph. (Gently rolling out of the throttle while still accelerating can delay the point at which the gas engine comes online to just over 30 mph.) When higher speeds are reached, more acceleration is needed, or the batteries are low, the gasoline engine enters the mix. At which point the process is almost exactly reversed, with the gasoline engine providing most of the power and the electric motor contributing when more torque is needed. Regenerative braking recovers energy and puts it back into the battery pack.
The 30-kW Sanyo battery pack sits under the rear carpet and forms the cargo area's load floor. Inside the thin metallic cassette sit 250 nickel-metal hydride D-cells wired in series and producing 330 volt. You read that right. D-cells,the same size as, but not interchangeable with, the ones found in flashlights. Unlike said flashlight, an external cooling vent in the driver's side rear window is part of the forced-air thermal management system. In hot weather it draws excess heat away from the pack, while an electric heater warms the batteries when the temperature drops. Ford says the system can handle temperature extremes from -40º F to +122º F.
Interior occupants aren't always so lucky because the gasoline engine shuts off when the vehicle is stopped for just about any length of time. Which means the air conditioning compressor isn't being driven, and the amount of cooling air coming into the cabin decreases quite rapidly in hot weather. A short burst of acceleration, however, is enough to cause the traction motor to quickly (400 milliseconds) spin the gasoline engine to life and restart the compressor. During the EPA city driving cycle, the motor is off as much as 40% of the time. According to Mary Ann Wright, Ford's director of Sustainable Mobility and Hybrid Vehicles, "Compared to a comparable non-hybrid two-wheel-drive V6 Escape, the hybrid version shows a 75% economy improvement in the city cycle and 50% in the combined cycle." Though the final fuel economy numbers have yet to be announced, Ford expects the Escape Hybrid's city mileage rating to approach 40 mpg and its combined city-highway mileage to hover around 30 mpg.
Maximum towing capacity is 1,000 lb (the base Escape can tow 1,500 lb, while the V6 is rated to pull 3,500 lb). Placing the battery cassette in back reduces fuel capacity by 1.5 gallons, drops cargo volume by just over 1.0 ft3, but leaves the rest of the interior measurements unchanged. Weight is up 325 lb compared to V6 models. Given the fact that most Escapes never leave the pavement, Ford's claim that this is a "no compromises" vehicle rings true. It soon will be followed by hybrid versions of the Mercury Mariner and the mid-size Ford and Mercury CD3 sedans.