petrochemist wrote:
From what I've heard temperatures make a huge difference to electric cars. Last month an electric car was used for the safety car at a race in the UK, The driver told me within a couple of laps the power had dropped by 10%. For more mundane use, if you use the heaters in winter your available range plumits.
I suspect the idea of MPG/e is to give a number that looks good for selling the car. It doesn't have to be useful if it impresses potential customers!
As long-time Prius owners (we currently have three and a Lexus ES300h among the four of us), we know the effects of Winter & Summer HVAC, roof racks with car top carriers, garaging the car overnight, and more.
In a hybrid, ALL energy comes from the gas engine. It's just that the kinetic energy of coasting, braking, etc. is stored in the battery for recycling during acceleration, and to charge the 12-Volt auxiliary battery that drives the lights and computers and such. So we might get 4-8 MPG better mileage in Spring and Fall.
I kept careful records of my first Gen 2 Prius Touring Edition. (It got 2-3 MPG less than a standard Prius due to the wider 17" tires)
Spring and Fall average 44.4 MPG
Winter average 40.1 MPG
Summer average 41.0 MPG
Driving to Florida from NC with a Sears X-Cargo on a pair of Thule roof rack rails 36.2 MPG
Just parking for 30 minutes with the AC on in summer will decrease mileage by 1-2 MPG, depending on outside temperature and set cabin temperature.
All that said, YES, mileage varies. But if we could just get a measure that made more sense for fully electric cars than 'MPGe', I think people would live with it. If it is measured under the same exact conditions as gas powered vehicles are tested, it would be useful. How about:
Miles or km per 60% of potential charge (i.e.; where the goal is to keep the state of charge between 20% and 80% for optimum battery life)
Miles or km per xxx kWh (where xxx = 60% of potential charge)
I predict that electric car adoption will pick up rapidly when rapid charging becomes a reality. If I can get charged to 90% in ten minutes or less, and go another 300 miles, it's probably time for another bio break, anyway.
Another factor in electric car adoption will be repairability. If you have to take a car to the brand dealer where you bought it, that's a show stopper for many. We need right to repair laws with TEETH in this country. Tesla hides behind "proprietary computer secrets" and other intellectual property law gibberish, so consumers pay an arm and a leg for repairs (or have to buy new cars if certain components fail!). Independent shops should have access to parts and tools and manuals.