All Prii are a bit heavy and their engines take a big hit in MPG during the first 6 minutes to warm up the the catalytic converter to keep the emission near zero as soon as possible because the Prii are design to fulfill the Kyoto Protocol Treaty. A Prius is designed to be a low emissions vehicle first before they are high MPG vehicles. Drive any Prius only 1 to 5 minutes at a time and the fuel efficiency drops to about 12-20 mpg but their emissions during those 1 to 5 minutes is the lowest in the industry for a gas engine car due to the Prii design priority of heating up the catalytic converter to near optimal temperature in 5 minutes and most efficient temperature withing 30 minutes. The impact on the Prius' MPG gets even higher as the driving temperature goes to freezing at 32 degrees Fahrenheit... when that happen - preheating the Prius engine for 60 minutes with the optional 400W Toyota Engine Block Heater can boost MPG to an amazing level... Grill blocking and driving the Prius longer thant 60 minutes per trip can lessen the thermal losses on a Prius.

The Prius Hatchback is slightly more aerodynamic than the Prius C so at speeds higher than 65 mph - there is some fuel effiency advantage which show ups in the USA EPA ratings but at under 55 mph the Prius Hatchback aerodynamics over the Prius c and v is much smaller and the lighter curb weight of the Prius C means the Prius C more efficient at climbing hills than all other Prii models and the MPG advantage becomes very clear. All Prii designs benefit from the use of low rolling resistant tires - and switching to regular tires or snow tires causes a Prius MPG performance to drop. All Prius benefit from being driven by a driver skilled in hypermiling - the overall MPG boost being from 5% to 20% .. For example using a Scangauge II OBDII monitor with a 2010 Toyota Prius III I've been able to achieve 58 mpg over about six years and 78,000 miles.