I prefer design 2 because the information in largest type is a number, and because it shows how much the fuel costs, rather than how much it saves, which is muddled thinking.
Greenhouse gas emission for electric vehicles should include the amount emitted at the power plant. This of course varies widely by the type of power plant, so take an average. The symbol "kW-hrs" is wrong. The correct symbol is "kW·h". A megajoule of gasoline, or any other fuel, makes sense (a liter of gasoline is about 29.5 MJ, so a megajoule of gasoline is 34 mL). A gallon or liter of electricity makes no sense at all. A kilowatt-hour is 3.6 MJ. Therefore all ratings should be stated in joules per meter, rather than MPGe. Expressing all forms of energy in joules will facilitate comparison with food energy expressed in kilojoules. The energy consumption per distance for the electric car is equivalent to 760.6 J/m. Assuming 41 kJ/g heat of burning gasoline and 0.72 g/mL density, the gasoline car consumes 2640 J/m. It is bad form to put a number in the denominator of a unit. This is one point on which the French are wrong (they use L/100 km). For liquid fuels, it should be µL/m (preferred because there is no prefix in the denominator) or L/Mm (easier to imagine when driving a car; the Lower 48 is about 4 Mm east to west). There should also be a sample label for hydrogen cars, for when they become available. Hydrogen will be sold in kilograms. We have had the metric system for over 30 years. It is easier to learn and easier to calculate in. Figures in metric units should be required; figures in obsolescent units should be optional, to disappear once highways are renumbered in kilometers and all fuels are sold in metric units. Pierre Abbat
