I used the Tesla link in your post, and noted no decline when using the heater or when driving in colder weather on the reported "savings". Same for the city vs highway driving selector.
I entered $1 per gallon and $1 per KWh to understand the numbers they are using. For 10,000 miles per year, at 20 MPG, Tesla correctly determines I'd spend $500 (I understand this isn't the cost, but it lets me easily verify Tesla is correctly computing MPG for gas engines).
For electricity, the number becomes 2,830 (which isn't meaningful as a dollar amount, BUT tells me exactly how many KWh Tesla says I'll use to drive 10,000 miles).
Tesla is claiming 3.5 miles per KWh of electricity it is charged with. Tesla's savings do not change with temperature, car load, type of driving, use of a heater, headlights or electronics. All of which seems odd to me.
I want to see how Tesla's energy efficiency compares to gasoline. Over here - »
en.wikipedia.org/wiki/Ga ··· uivalent a claim is made that one gallon of "average" gasoline (varies by region and time of year) is about 34 KWh of power.
Tesla claims to get 3.5 miles per KWh. I multiply 3.5 times 34 (the KWh in a gallon of gasoline) and Tesla is claiming to get a gasoline equivalent of about 120 miles per gallon regardless of driving conditions or load.
Their vehicle will have inertia, and not all inertia can be recovered when stopping, likely most can't. The vehicle will experience wind drag, and must have friction (friction is required on tires to attain acceleration and to control a vehicle, it permits for example steering ... it is often referred to as rolling resistance).
The NHTSA has a longish report on tire efficiency, which includes a lot of information about vehicle efficiency as well at »
www.nhtsa.gov/DOT/NHTSA/ ··· /Vehicle Research & Test Center (VRTC)/ca/Tires/811154.pdf per the energy loss diagram on pdf page 18 of the report a typical vehicle loses 18% of it's energy when idle, 2.2% for accessories, 5.6 is lost in the drive train, 62.4% is lost due to engine inefficiency, 2.4 percent due to air drag, and 4.2% to rolling resistance.
Of the factors above, 62.4% of the loss is from the engine, 5.6 is lost due to drive train, and 18% lost due to engine idle.
Assuming Tesla is 100% energy efficient at moving your power from the cord to the tires (no engine or drive train issues) a Tesla car could be 75% more energy efficient than a gasoline car per the report cited above.
Tesla is claiming 120 MPG effective mileage. Assuming 3/4 of the energy would be wasted by an internal combustion engine, a similar gasoline powered vehicle would produce 30 MPG (1/4 the MPG claimed by Tesla).
The Tesla weighs 4,647 lbs empty (curb weight) per - »
www.teslamotors.com/models/specs ... when I visit Automobile Magazine, and want to compare the Tesla to similar vehicles. I get a list (which I hope is included properly in this link, if not my apology in advance) - »
vehicles.automobilemag.c ··· are.htmlComparable cars seem to be Porsche Panamera S Hybrid, Audi S4 and Aston Martin Rapide. The Tesla is well priced within this group. It isn't the heaviest (the Porsche is).
However, MPG doesn't seem to match up exactly. Assuming 30 MPG using the conversions above is reasonable, then only the Audi comes close with a highway MPG of 28, but a city MPG of 18. The vehicle in the group with the closes overall MPG highway vs city is the Porsche which claims 24 MPG highway and 20 MPG city.
After factoring out for engine, drive train, and idle energy losses, Tesla is claiming a higher effective MPG than any comparable vehicle.
The mileage claim of Tesla, even after discounting for energy efficiency claims, seems a bit of a stretch to me. Though that is just my opinion.