Are my calculations off or the EPA’s?

Are my calculations off or the EPA’s?

All the recent talk about the low EPA range number for the Porsche Taycan got me interested in revisiting what my car’s window sticker for my 2104 MS85.

First the EPA statement about the origin of their costs calculations:

“Actual results will vary for many reasons, including driving conditions and how you drive and maintain your vehicle. The average new vehicle gets 23 MPG and costs $11,500 to fuel over 5 years. Cost estimates are based on 15,000 miles per year at 0.12 per kW-hr. MPGe is miles per gasoline equivalent. Vehicle emissions are a significant cause of climate change and smog”

Ok, what I can’t figure out is where they came up with a gasoline cost of $11,500 over 5 years, at 23 MPG. I think the cost over 5 years is less. 15,000 miles / 23 MPG equals 652 gallons of gas per year or a total of 3,260 gallons over 5 years. That works out to an avg gas price of $3.53 per gallon. Since the EPA statement and MPG and miles traveled per year are for the average car on the road, why is the gas price not an average gas price? It may be average for CA, but the EPA numbers are presumably not CA centric.

Here in CT in my town, the present price per gallon for regular gas is $2.73. 3,260 gal x $2.73 = $8,899 for 5 years. Am I missing something here? The cost of kWh the EPA statement cites is certainly a national average because I know that I pay $.20 p kWh and from what I have read here, people in CA pay more than “$.12”. So, the EPA calculations use avg miles per year, avg MPG, avg electricity costs, yet their numbers equal a far above avg cost per gallon for gas.

Lastly, this is meant to be an academic question/discussion, not how the EPA calculates range or their MPGe numbers.

andy.connor.e | December 21, 2019

Thats why you have to take the estimates with a grain of salt, and do the research that you have done to find out what your actual savings are. Gasoline is $2.70/gal for me, and electricity is $0.112/kWh.

And yes your calcs are correct | December 21, 2019

Also consider that most premium, luxury, and performance vehicles use premium gas, which can be $.20 to $.40 more expensive. Not sure if the EPA uses this in the calculation, but should when looking at the Model S/X. It is less clear with the Model 3 if premium gas or regular should be used as a comparison.

jordanrichard | December 21, 2019

Ok, I am not looking for answers about range and such or gas savings. I know how much I have saved, that’s over $18,000 over the course of 174,000 miles.

I am just asking using the EPA provided numbers on the window sticker how they came to a $11,500 cost to fuel a car over the course of 5 years, getting 23 MPG.

TT, my personal savings is based on the cost of premium gas because my previous car took premium gas, my wife’s car takes premium and lastly the performance that my car has would typically be found in high performance cars that require premium. Presently premium is $3.23 which puts it $.50 more expensive.

It’s funny that they provided a per Kwh price and yet didn’t provide the per gallon price they are using in their calculations. | December 21, 2019

I did find this statement from

"The price of gasoline listed on new vehicle labels is based on projections from the U.S. Energy Information Administration for the applicable model year. It is typically updated annually in coordination with the Department of Energy. The sample labels include an example price that is intended for illustrative purposes only."

It also states they currently use $3.70 per gallon. Maybe an average across the USA?

NKYTA | December 21, 2019

TT, I would expect it is less, unless it is per capita.

jordanrichard | December 22, 2019


I was in LA for the Cybrtrk reveal and the local price for Regular was $3.89 where as here in CT it was about $2.60 and we have the some of the highest gas prices on the east coast.

It is ironic that the EPA/DOT “Fuel Economy” section of the window sticker providesnumbers and the source of those numbers, except the price of gas that they are using in their calculations.

FISHEV | December 22, 2019

"Cost estimates are based on 15,000 miles per year at 0.12 per kW-hr. MPGe is miles per gasoline equivalent."

That's really low based on actual NET cost per kWh vs. spot costs. All the taxes and fees have to be included. I'm in one of the lowest electricity cost states in US at $0.13 per kWh but after fees and taxes, my actual is $0.31. I do sign up for "Blue Sky" and "Low Income Help" adders but that would only get me down to $0.28 per kWh.

Likewise using 23 mpg over states the gasoline gasoline costs. I think Prius is the top transition from car for Tesla and likely other EV's. 90% of people looking at EV's are coming from cars with a reasonable mpg, 32 mpg on the Subaru Legacy for example.

My net savings using Tesla's $0.28 per kWh vs. Subaru's 32 mpg at OR's average of $3/gal and using 15,000 average.

Electricity $1,106
Gasoline $1,406

So not a big savings.