Found this on Wiki, almost an instantaneous start on later cars. One does wonder if today's technology could improve on the MPG.
Colin
Stanley Steamer
Perhaps the best-known and best-selling steam car was the Stanley Steamer, produced from 1896 to 1924. Between 1899 and 1905, Stanley outsold all gasoline-powered cars, and was second only to Columbia Electric in the US.[2] It used a compact fire-tube boiler to power a simple double-acting two-cylinder engine. Because of the phenomenal torque available at all engine speeds, the steam car's engine was typically geared directly to the rear axle, with no clutch or variable speed transmission required. Until 1914, Stanley steam cars vented their exhaust steam directly to the atmosphere, necessitating frequent refilling of the water tank; after 1914, all Stanleys were fitted with a condenser, which considerably reduced their water consumption.
In 1906 the Land Speed Record was broken by a Stanley steam car, piloted by Fred Marriott, which achieved 127 mph (204 km/h) at Ormond Beach, Florida. This annual week-long "Speed Week" was the forerunner of today's Daytona 500. This record was not exceeded by any car until 1910, and, though Barber-Nichols later held the US steam-powered record,[citation needed] the FIA international record was only broken by another steam car on August 25, 2009 by Team Inspiration of the British Steam Car Challenge (see below).
Doble Steam Car
Attempts were made to bring more advanced steam cars on the market, the most remarkable being the Doble Steam Car[5] which shortened start-up time very noticeably by incorporating a highly efficient monotube steam generator to heat a much smaller quantity of water along with effective automation of burner and water feed control. By 1923, Doble's steam cars could be started from cold with the turn of a key and driven off in 40 seconds or less. When the boiler had achieved maximum working pressure, the burner would cut out until pressure had fallen to a minimum level, whereupon it would re-ignite; by this means the car could achieve around 15 miles per gallon (18.8 litres/100 km) of kerosene despite its weight in excess of 5,000 lb (2,268 kg). Ultimately, despite their undoubted qualities, Doble cars failed due to poor company organisation and high initial cost.
