Energy Efficiency
In June 2006, Tesla Motors reported the Roadster's battery-to-wheel efficiency as 110 W·h/km (17.7 kW·h/100 mi) on an unspecified driving cycle—either a constant 60 mph (97 km/h)) or SAE J1634 test—and stated a charging efficiency of 86% for an overall plug-to-wheel efficiency of 128 W·h/km (20.5 kW·h/100 mi).
In March 2007, Tesla Motors reported the Roadster's efficiency on the EPA highway cycle as "135 mpg equivalent, per the conversion rate used by the EPA" or 133 W·h/km (21.5 kW·h/100 mi) battery-to-wheel and 155 W·h/km (24.9 kW·h/100 mi) plug-to-wheel.
In August 2007, Tesla Motors' dynamometer testing of a Validation Prototype on the EPA combined cycle yielded a range of 221 mi (356 km) using 149 W·h/km (23.9 kW·h/100 mi) battery-to-wheel and 209 Wh/km (33.6 kW·h/100 mi) plug-to-wheel.
In February 2008, Tesla Motors reported improved plug-to-wheel efficiency after testing a Validation Prototype car at an EPA-certified location. Those tests yielded a range of 220 mi (350 km) and a plug-to-wheel efficiency of 256 mpgge, or 199 W·h/km (32.1 kW·h/100 mi).
In August 2008, Tesla Motors reported on testing with the new, single-speed gearbox and upgraded electronics of Powertrain 1.5 which yielded an EPA range of 244 mi (393 km) and an EPA combined cycle, plug-to-wheel efficiency of 174 W·h/km, 630 kJ/km (28 kW·h/100 mi).
In 2007, the Roadster's battery-to-wheel motor efficiency was reported as 88% to 90% on average and 80% at peak power. For comparison, internal combustion engines have a tank-to-wheel efficiency of about 15%. Taking a more complete picture including the cost of energy drawn from its source, Tesla reports that their technology, assuming electricity generated from natural gas-burning power plants, has a high well-to-wheel efficiency of 1.14 kilometers per megajoule, compared to 0.202 km/MJ for gasoline-powered sports cars, 0.478 km/MJ for gasoline-powered commuter cars, 0.556 km/MJ for hybrid cars, and 0.348 km/MJ for hydrogen fuel cell vehicles.
Read more about this topic: Tesla Roadster
Famous quotes containing the words energy and/or efficiency:
“I have witnessed the tremendous energy of the masses. On this foundation it is possible to accomplish any task whatsoever.”
—Mao Zedong (1893–1976)
“Nothing comes to pass in nature, which can be set down to a flaw therein; for nature is always the same and everywhere one and the same in her efficiency and power of action; that is, nature’s laws and ordinances whereby all things come to pass and change from one form to another, are everywhere and always; so that there should be one and the same method of understanding the nature of all things whatsoever, namely, through nature’s universal laws and rules.”
—Baruch (Benedict)