History's Innovative Autos

Jet engines
During World War II, automotive companies inspired by advances in jet engines tried to adapt the technology for use in cars. Chrysler's so-called Turbine Car (left) used a rotary fan, propelled by rapidly burning fuel, to drive the vehicle. By 1963, such experimental turbine engines could run on gasoline, jet fuel, or even vegetable oil, and like actual jet engines, they provided powerful acceleration. But they also suffered from significant problems, among them high fuel consumption. Rover's Jet-1, for instance, traveled just six miles per gallon.

Nuclear propulsion
The Ford Nucleon concept car symbolized the 1950s Atomic Age, when nuclear energy seemed to offer a clean alternative to traditional fuels. Engineers proposed that the Nucleon (left) would be powered by a small nuclear reactor, which would split atoms to release energy in the form of heat. The heat would convert stored water into steam, and the steam would propel turbine fans to drive the engine. But the envisioned pint-sized reactors Ford was counting on to be developed did not materialize, even as recognition of the inherent danger did. In the end, no working prototypes were built.

Steam
Steam cars were in vogue by the late 19th century. Of these, the Stanley Steamer (left), produced from 1896 to 1924, was the most popular, often outselling conventional gas-powered cars. It even reached a record-breaking 127 mph in 1906. The Steamer burned gasoline or kerosene to heat water in a boiler; the boiling water then generated steam, and pressure from the steam powered the engine. Their price tag doomed steam cars by the start of the Great Depression, however. Steamers cost thousands of dollars apiece, compared to Ford's Model T, which sold for less than $500.

Compressed air
In 1979, as America found itself embroiled in an energy crisis, Missouri-based engine designer Terry Miller built a car that ran on an abundant, zero-emission fuel source—air. Compressed-air engines had been used in some locomotives and trucks since the 1800s, but Miller streamlined the design for his Air Car One (left). Pressure generated by the release of compressed air from onboard tanks drove the car's engine. Miller's vehicle was never commercially produced, but interest remains. India's Tata Motors, for one, may have a compressed-air car on the country's roads by 2008.

Electric
Automakers have produced electric cars off and on for over a century. Ohio-based Baker Motor Vehicle Co. was among the most successful, selling thousands of its electrics to wealthy consumers (including Thomas Edison) from 1899 to 1915. But while each Baker (left, a 1912 model) ran on no fewer than 12 cell batteries, its top speed was just 14 miles per hour. In contrast, many less expensive, gas-powered cars could exceed 40 mph. Today, as gas prices soar and battery technology improves, all-electric cars might well make a comeback.

Gas-electric hybrid
In 1901, Czech engineer Ferdinand Porsche unveiled the Mixte (left). French for "mixed," the car was a forerunner to today's gas-electric hybrids, which use less gasoline and create fewer emissions than conventional gas-powered cars. But unlike Porsche's later sports cars, the Mixte was too far ahead of its time. The four-seater model required nearly two tons of batteries, which made it too expensive to be produced in bulk. (The model seen here is a two-seater.) Improved battery technologies have helped reduce costs and allow modern hybrids like Toyota's Prius to sell increasingly well.

Solar electric
In 1987, General Motors harnessed solar rays to help run its Sunraycer experimental racing vehicle (left). The Sunraycer's photovoltaic cells converted the sun's energy directly into electrical energy; the electricity then powered an electric motor that drove the car. Although similar technology is still used in special aerodynamic racecars, any purely solar-powered road vehicle designed to meet general safety standards would be larger and much heavier than the Sunraycer, requiring more power than can yet be generated to achieve highway speeds.

Biofuels
Henry Ford (left, at the wheel of a Model T) designed his "Tin Lizzie" to run on either gasoline or a hemp-based fuel. But with the discovery of large crude-oil deposits in the early 20th century, oil prices dropped and gasoline derived from the oil became Ford's and other carmakers' fuel of choice. Unlike fossil fuels, biofuels come from renewable resources, typically plants. Although biofuels have many advocates, skeptics point out that they currently require too many resources to be used on a widespread commercial basis.

Hydrogen fuel cells
Fuel cells combine fuel (usually hydrogen) and oxygen to produce electricity through chemical reactions similar to those that occur in batteries. While some automakers are now trying to develop hydrogen fuel-cell cars, General Motors actually designed its own, the Electrovan, as early as 1966. While the Electrovan (left) could travel up to 70 mph and 120 miles between refuelings, it was too expensive to produce commercially. Recent advances have made affordable fuel cells more likely, and in 2003 the U.S. Congress pledged $1.2 billion to make such vehicles cost-effective by 2020.