Hello all....we leased a 2014 PPI about a month ago, and so far have about 600 miles on it. Still have about 1/2 of the original tank of gas, and the trip computer says we have been around 60% EV. SO how accurate is that MPGe figure? Am I really getting 100+ mpg in this thing?
Congratulations on joining the plugin revolution! If you have driven 60% EV then you would have driven 40% of your miles on gasoline. If you drove 100 miles total then your total gasoline consumption rate would be 100 MPG if you drive those 40 gas miles on 1 gallon (40 MPG without using the plugin battery charge). Of course, you actually used 1/2 a tank so you drove farther but I'm using 100 miles to simplify the math example. Your driving a Prius, so it's pretty likely you are getting over 40 mpg on gasoline alone. So yes, welcome to the 100+ MPG club. Note, that this is total combined MPG. MPGe is something else. MPGe is a way of converting electricity into the equivalent energy of a gallon of gasoline so that you can calculate your combined efficiency of using both electricity and gasoline to drive those 100 miles. For this purpose, 33.7 kWh is defined to be equivalent to the energy in a gallon of gasoline. Let's say you used 15 kWh of electricity from plugging in the car for 5 full battery recharges using 3 kWh of electricity each time that gave you a 12 mile EV driving range (12 miles x 5 charges is 60 miles EV). You then drove the remaining 40 miles on gasoline alone at 50 mpg. Your total MPG would be 125 because you would have used 0.8 gallons of gasoline at 50 MPG to drive 40 miles (0.8 x 50) so 100 miles / 0.8 gallons is 125. Your total combined MPGe would be 15 kWh / 33.7 kWh or the equivalent energy of 0.445 gallons of gasoline. Add this to the 0.8 gallons of real gasoline and your total gasoline equivalent is 1.245 gallons. Now divide that 100 miles of distance by 1.245 equivalent gallons and your total combined MPGe is 80.32 MPGe. Total combined MPG: 125 Total combined MPGe: 80.32 The total combined MPG accounts for only the gasoline used but not the plug power. The total combined MPGe accounts for both. MPGe can also be used to describe just the electrical efficiency itself just like MPG can be used just to describe the hybrid mode gasoline efficiency without plug power. Note that the Prius (like most plugin cars) displays how many kWh of plug power you have used while driving but that doesn't include some power lost during the battery charging process (around 15%). The MPGe number includes the power lost during charging so it is based on the power as measured at the electrical socket where you plug in. This was probably way more than you wanted to know right now... Have fun with your new Prius!
Nobody told me there was going to be math!! But I think I understand. The trip computer (as well as the thing that pops up each time I turn it off telling me how far I went) doesn't take the electric use into account when figuring mpg. But I can do the math myself to figure it out using the kwh count. So far we are very pleased with this car, which is primarily my wife's. She is mostly driving in town....usually short trips...and we think this will be ideal for her. We leased it in order to determine whether or not it will work for us, and so far it seems like it will do great. In 2 years we'll likely buy one. (hopefully with a bit more EV range by that time).
Welcome. When it comes to the EV quantity shown, keep in mind that it represents driving with the engine off while in EV mode only. Driving with the engine off while in HV mode doesn't get counted. Driving at speeds faster than 62 mph doesn't either. The catch is, both will draw from that plug-supplied electricity though. That's why MPG can be +100 even though you aren't EV driving. Long story short, just keep plugging in. The end result will be a significant reduction in gas consumption.
