MPG and Power: Driving alone vs. driving packed

On a road trip where I had a couple hundred pounds of equipment my highway mpg dropped from what would normally have been 57 mpg to 53 mpg. (Although it was also 97 degrees and I had the AC on...).
And everybody said:Road trip!

 

We find

We find that outside air temp has the most effect followed by raining or not raining; 0 deg outside we get only 34 mpg, but 70 deg sees 55 mpg per tank where we measure every drop that goes in (not what the in car display says) divided by actual miles. The display reads 2 to 3 mpg higher than actual milage. On in town driving with lots of 30 mph zones we have seen as high as 72 mpg actual when warm outside. Yes, every 100 lbs you add will decrease you milage about 1/3 mpg. Use the battery as much as possible. The engine likes to kick in @ 35 mph, so we like to set the speed control @ 34 or even 33 mph. We always use the speed control and use resume also in Eco mode as the system is programmed to use the least amount of fuel to resume to your preset mph. We have had the 2012 C in Eco mode the entire 18 months of ownership as power is still available if you just must. It is a good idea to blow it out once a month and use the brakes hard once a month otherwise the brake drums and disc rust up due to none use. Yes Bill is an automotive engineer which helps a lot. Another couple good ideas are slow down 5 mph if raining or driving into a head wind or heavy loads in the car and of course drive the speed limit or below on the speed control, never pull out in front of cars, use the electric motor up to at least 10 mph (use the in car display) and coast as much as possible in drive, never in neutral. Our only speeding ticket in the last 40 years was 25 years ago in a new transition zone, totally unintentional. Let the other traffic go by you and just glance at you mpg display and smile. It is counter productive to spend $200 on a speeding ticket and lose 10 mpg at the same time; that is paying twice for it. Every 10 mph faster you go you lose about 9% mpg! 55 mpg vs less than 50 mpg for example. How much weight is in the car is sweating the small stuff.

There are so many factors that effect mpg and certainly AC on is a big 4 mpg loss (% wise) which is a normal loss with any car. Someone in a nonPrius getting may drop from 19 to 17 2/3 mpg ( the same %) and never notice the loss without a mpg display because they are typically insensitive to the effeciency we strive for. Other factors are altitude, altitude loss or gain on your trip, head wind vs tail wind vs cross wind effects, type of road surface you are driving on, out side air temp, humidity, tire inflation level, whether on speed control or not, windows up or down, 15" vs 16" tires (15" are best), angle or rake of car which is effected by rear end loading, and on and on. See comments below for more insight. Just get educated on your Prius, mpg in general and for the Good Lord sake, use common sense and your head. By owning a Prius we are making a statement to the world; effeciency is more important than reckless use of God's non renewable blessings! Just remember, the lower the mpg in general the more we are adding CO2 and CO to the air we breath and our children, grandchildren and great grandchildren have to breath. That is why lead basically is no longer added to gasoline; it was polluting the air, ground and seas and oceans and even the water we all drink - wonder if that has anything to do with the dramatic rise in autism in kids?