mileage

You've no doubt come across this before, but it's worth repeating whenever someone does a story on the American auto fleet's fuel economy: The New York Times reports that "the average fuel economy in 2009 model cars, vans, pickups and S.U.V.'s was 22.4 miles per gallon -- an increase of 7 percent, or 1.4 miles per gallon, over 2008 figures." Environmentalists, we are told, hailed the news. Which means the fleet average is now just 2.6 mpg shy of what the Ford Model T achieved 102 years ago. The good news is that embarrassing record is for lack of trying. If we're lucky, the Volt and Leaf are…
Which wastes more fuel? (and thus produces more carbon dioxide). This is a difficult to question to answer for a variety of reasons. The main reason is that a speed change from 71 mph to 70 mph is different than a reduction from 56 to 55 mph. First, let me be clear that the question of how much fuel is wasted using daytime running lights (or DRL as they are called) has already been addressed. The first source I found was howstuffworks.com Assumptions The daytime running lights on a car run at about 100 watts (for the pair) The energy density of gasoline is 1.21 x 108 Joules/gallon. A car is…