Here's some Auto stuff..
This is the age of electric and hybrid electric vehicles. Every company is coming up with its HE (hybrid electric) versions of the cars claiming that they improve the fuel economy. Some numbers tell that the Prius has a fuel economy of 48 miles per gallon (mpg) on city cycle, Honda Civic hybrid was rated 40mpg whereas the latest hype is about Chevy Volt, claiming 60 mpg (combined mode) and 93 mpg (electric only mode).
The basic assumption lies in the fact that this equivalent fuel economy is higher because unlike normal vehicles, in HEVs or EVs less amount of gasoline is burnt. They had to find some way for comparing the fuel "burnt" as "electricity" (which produces no emissions) to the fuel that is burnt in conventional vehicles to come up with a number: miles per "gallons" (where there are really no "gallons" of fuel "burnt" in electric vehicles).
"To reach this number EPA created a conversion factor between quantity of electric energy (KWHr) and volume of gasoline (gallons). They did this by dividing the heating value of a gallon of gasoline by the energy in a KWHr of electricity to get a conversion factor of 33.7 gallons/KWhr." ..states the article below
But is this the right way to do it? Should they account for the energy losses in "preparing" that electricity? after all we should be concerned more towards reducing the fossil fuel usage rather than "increasing" the power train efficiency per se
..and if they do what are the new numbers? are they more realistic?
This is a very nice article which sheds light on this issue. One of our profs shared it with us. You guys will find it interesting