This is an installment in a series of posts looking back on show cars that we feel deserved a little more attention than they got. If you have a suggestion for a Forgotten Concept topic, please shoot us a line or leave a comment below.

Briggs & Stratton Hybrid

First Seen: 1979 San Francisco Import Car Show



Description: Fuel-efficient hybrid commuter vehicle featuring a small gasoline engine augmented by an electric motor

Sales Pitch: “We feel that a properly designed parallel hybrid can virtually eliminate all the performance-based barriers to customer acceptance of an electric car as a primary personal car.”

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Details: The Hybrid was a forward-thinking concept car from the unlikeliest of sources: small-engine manufacturer Briggs & Stratton. Eager to promote the company’s new air-cooled, horizontally opposed 2-cylinder engine, Briggs & Stratton set out to develop a concept car using its new powerplant as the centerpiece of the novel powertrain. The Hybrid’s drivetrain paired the new Briggs engine, which was good for 18 horsepower, with an 8-horse Balder electric motor. This parallel hybrid arrangement was enabled by a Borg-Warner “Duo Cam” automatic clutch that allowed the gas engine and electric motor to work individually or in tandem as needed.

Power for the electric motor was stored in battery pack that consisted of 12 6-volt batteries located under the rear cargo floor. A separate 12-volt battery was used to power the car’s headlights and other accessories. The Hybrid Concept’s 4-speed-manual transmission was a Ford Pinto unit. To accommodate the substantial weight of the battery pack (about 1000 pounds), a second rear axle was incorporated into the car’s design. The extra axle was used exclusively to bear the weight of the batteries; it was not fitted with brakes, and it was not connected to the powertrain.

To reduce development time and cost, Briggs & Stratton engineers borrowed the chassis of the Marathon C-360 electric van, which conveniently featured a dual-rear-axle setup. The bodywork was farmed out to Brooks Stevens Design Associates– the final design was penned by Brooks himself, along with his son Kip.

The fully functional concept was passed around to various buff books after its debut, with test results varying slightly by magazine. Motor Trend reported the Hybrid Concept returned 50 mpg in gas-only mode, and 85 mpg when operating as a hybrid–both impressive figures for the era. Less impressive was the car’s performance. Top speed was a reported 55 mph, while a 0-50-mph run consumed a frightening 35 seconds. In electric-only mode, the top speed dropped to 40 mph, which the car could travel at for roughly 60 miles before depleting the batteries. Charging the battery pack took 8 hours using a household 110-volt outlet. An updated version of the Hybrid Concept added regenerative braking to the mix, somewhat improving the car’s range and hybrid fuel economy. Even with the regenerative brakes, the car needed to be plugged in periodically to operate in hybrid mode.

Unlike modern hybrids, the Briggs & Stratton Hybrid made no use of computer control. Thus, switching between drive modes was left entirely to the driver, who was expected to know which mode would provide the most-efficient operation in any given situation. The driver was also required to operate the manual transmission.

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CG Says: Apart from the clunky dual-rear-axle design, the Briggs & Stratton Hybrid Concept was a miracle of predictive engineering. Given modern computer control and higher-capacity batteries, the Hybrid Concept might have come close to mirroring the performance of more-modern hybrid vehicles. The car’s styling is pure Eighties, but in a good way–to these eyes, it comes off looking a little like a Dodge Omni 024 or Plymouth Horizon TC3. Good news: the Briggs & Stratton Hybrid Concept is still around, and can be viewed at the company’s Powerhouse Museum in Milwaukee, Wisconsin.

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