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Singing the electric Saab Sonnett: Motoramic TV

Ezra Dyer
August 13, 2013

In the mainstream car market, electric vehicles are defined on one end by eco-mobiles like the Nissan Leaf and the other by the luxury performance cars like the Tesla Model S and upcoming Mercedes-Benz SLS AMG E-Cell. As for used cars, there’s really not much to choose from, since the modern electric renaissance is still only a few years old. But in a smattering of garages around the country, dedicated tinkers are reimagining classic sports cars and mating electric power with vintage aesthetics. For instance, what would a Saab Sonnett have been like if lithium batteries were around in 1969? Eric Kriss of Waltham, Mass., decided to find out.

The Sonnett’s stock V4 got hoisted, replaced by an 80-hp electric motor and a 12.5 kW lithium iron phosphate (LiFePO4) battery pack that provides around 70 miles of range. The Sonnett’s column-mounted manual transmission remains. “Because the power and rpm range match the original engine pretty closely, you can retain the stock transmission,” Kriss says. You might shift gears less often than you would in an original Sonnett, though, since the electric motor’s 110 lb-ft of torque is available from zero to about 4,000 rpm.

The result is a smooth, quiet, deceptively punchy Sonnett. I’ll admit that I’ve never ridden in a stock, internal-combustion Sonnett, but I doubt that the original powertrain would offer the effortless fourth-gear surge of torque that allows Kriss’ screaming-blue Saab to knife through the chaos of suburban Boston traffic. It’s not overpowered, by any means, but electric propulsion seems to suit this car. “Lightweight sports cars with relatively modest power are ideal for electric conversions,” Kriss says. Since you’re not looking for a three-second 0-60 time, you can use light-duty components and retain the stock transmissions—Kriss’ other electric car, a replica Porsche 356 Speedster, also uses a manual transmission. That car carries a stouter, 23.8 kW battery pack that’s good for 140 miles or so.

Cars like the Sonnett become ever more esoteric with each passing year, with parts increasingly hard to find, leading Kriss to predict that electric conversions might soon become an accepted alternative to an engine rebuild or replacement. As for the heresy of repowering a classic car using a high-performance golf cart motor and a bundle of Chinese submarine batteries, Kriss says the reactions vary. “The Porsche people can be skeptical,” he says. “The Saab crowd generally thinks it’s cool.”