I like this Camry Hybrid review best as it explains in detail, the engine improvements and car's body improvements to improve it's aerodynamics.

http://www.hybridcars.com/compacts-s...-overview.html

 

Seems like they've come a long way since my 2007! The two things that for a split second almost made me go to the dealership are the nicer interior (ie: not so cheap looking) and the larger trunk space. I hope they stay on this track with future models so I can benefit from their refinements when it's time for me to buy another car!