2018 Honda Clarity Plug-In Hybrid debuts at 2017 New York auto showEnlarge Photo
Those included two large high-pressure hydrogen storage tanks, one under the rear seat and a second behind it at the front of the trunk.
The brief for the rest of the fuel-cell powertrain was to fit it all under the hood, in the same space as a V-6 engine and transmission would occupy, including the fuel-cell stack, the electric drive motor, and associated power electronics.
That left plenty of under-hood room for the plug-in hybrid version's 1.5-liter Atkinson cycle 4-cylinder engine, which both generates electricity to power a 135-kw (181-hp) electric motor and recharges a 17-kilowatt-hour lithium-ion battery pack at the rear of the car.
That battery capacity will provide "at least 40 miles" of EPA-rated range, Honda has said, but further specifications and details won't come until very late this year. (The Clarity Plug-In, unlike the other two, will go on sale as a 2018 model rather than a 2017.)
The all-electric version of Clarity, meanwhile, has a larger battery, a 25.5-kilowatt-hour lithium-ion pack that sends electricity to a slightly less powerful 120-kilowatt (161-horsepower) electric motor driving the front wheels, rated at up to 221 lb-ft of torque.
The biggest challenge of designing one car to accommodate these three very different powertrains, Guzowski said, was managing the weight distribution.
The battery packs for the two plug-in versions are located under the rear seat, ahead of the rear axle, adding weight at the rear, where the smaller of the two hydrogen tanks sat.
Even the all-electric version uses an air-cooled battery pack, rather than liquid thermal conditioning, meaning there are no radiators to compensate by adding weight at the front of the Clarity Electric.
The engineers "moved the pieces around" as best they could, he said, including such heavy items as the Clarity's standard 12-volt accessory battery.
The elephant in the room, though, is the low battery range of the Clarity Electric.
When it hits the market later this year, the battery-powered Clarity will have a range roughly the same as that of the tiny Smart ForTwo Electric Drive, and lower than the rated ranges of every compact electric hatchback sold today.
Chevrolet Bolt Concept - 2015 Detroit Auto Show live photosEnlarge Photo
So where did that decision to offer only 80 miles come from?
Guzowski was appropriately discreet, but he did admit that by January 2015, the program and its planners and engineers were "well on our way" to the final vehicle introduced last month.
That was the month in which General Motors CEO Mary Barra dropped a bombshell at the Detroit auto show, announcing what became the 2017 Chevrolet Bolt EV electric car