Via RealClimate.org
What reduces emissions more?
A. Someone swapping their old SUV (which gets 12 miles per gallon) for a hybrid version (18 mpg) or
B. someone upgrading their 25 mpg compact to a new 46 mpg Prius?
(ignore for a minute manufacturing issues or driving habits and assume the miles driven are the same).
The surprising answer is here.
Grrr I got it wrong. My mind went to The 12 Days of Christmas where you need several Priussss, so I assumed that if you wanted it, it must be IT.