Home / Uncategorized / Total Cost of Ownership Calculator Assumptions

The PGR Calculator was built on the following platform of assumptions:

  • “Interest Rate” refers to the amount of interest paid on car payments. “Discount Rate” reflects the time value of money for net present value calculations.
  • Total Cost of Ownership (TCO) – includes car payments and the cost of fuel (gas, diesel and electricity). TCO does not include residual battery value or the additional cost of battery maintenance. Maintenance costs are not initially included in the incremental cost, but users may enter annual costs savings for one vehicle over another in the “Advanced Options” section. Reports have been published forecasting lower maintenance costs for electric vehicles.[1]
  • All Battery Electric Vehicles are assumed to drive all of the annual miles driven as determined by the user (BEVs have no internal combustion engine). This means that for the purposes of this calculator, users are charging their vehicle as many times as necessary to complete the annual vehicle miles driven.
  • Base level MSRPs have been used for all vehicles that are currently available to the mass market. Some vehicle prices are our best estimate. For example, the MSRP for the Nissan Leaf has not been publicly released but the Nissan press release said it would be priced similarly to other mid-level sedans. This could be anything from $20,000-30,000 and we chose $27,000. In the case of the Ford Escape plug-in, we took the MSRP for the hybrid Escape and added $15,000 (the cost of a typical plug-in conversion).
  • Most of the Internal Combustion Engine vehicles were selected based on the Top Ten Best Selling Vehicles of 2008.[2] All MSRP and MPG figures for vehicles currently available on the market refer to 2008-year models. MSRP numbers come from http://www.cars.com and MPG numbers come ftom http://fueleconomy.gov. The Jetta TDI was included because of its ‘Green Car of the Year’ award by Green Car Journal. The list of plug-in vehicles included to date is by no means all-inclusive; RMI will work to include additional makes and models in the near future.
  • RMI expects the cost of plug-in vehicles to come down significantly in the future with scale and advances in technology.
Constant Inputs[3]
Price of Electricity $0.11/kWh
BTUs per Gallon of Gasoline 125,000
BTUs per Gallon of Diesel 139,000
BTUS per Barrel of Oil 5,800,000
Well to Pump Efficiency of Gas 79.8%
Well to Pump Efficiency of Diesel 83.7%
Duration of Car Payments 5 yr
CO2 Equivalent Emissions of Electricity 684 g/kWh
Well to Wheel CO2 Equivalent Emissions of Gasoline 11,500 g/gal
Well to Wheel CO2 Equivalent Emissions of Diesel 10,700 g/gal


Generation Mix Assumed

In order to calculate the CO2 equivalent green house gas emissions relating to electricity use, the following generation mix was assumed:[4]

Electricity Generation Mix and Power Plant Emissions Factors (g/kWh)
Power Plant Generation Mix CH4 NO2 CO2
Residual Oil 2.7% 0.009 0.004 833.9
Natural Gas 18.9% 0.030 0.012 504.8
Coal 50.7% 0.012 0.011 1084.0
Biomass 1.3% 0.041 0.117 1086.0
Nuclear 18.7% 0.000 0.000 0.0
Other (wind, hydro, geothermal) 7.7% 0.000 0.000 0.0
Totals 100% 0.313 0.009 681.6
CO2 Equivalent Multiplier 25 298
Total Emissions (g/kWh) 684.72

Multipliers of 25 and 298 were used for CH4 and NO2 emissions respectively.

CO2 equivalent green house gas emissions of Gasoline and Diesel use were calculated using the Argonne National Laboratory’s GREET figures:

Emissions from combustion of Gasoline (g CO2eq/gal): 8,909

Well to Pump Emissions of Gasoline (g CO2eq/gal): 1,800

Total[5] (g CO2eq/gal): 10,709

Emissions from combustion of Diesel (g CO2eq/gal): 9,802

Well to Pump Emissions of Diesel (g CO2eq/gal): 1,653

Total[6] (g CO2eq/gal): 11,455


Subsidies

Federal subsidy figures were calculated based on the kWh battery capacity of plug-in vehicles: $2500 + $417 x each kWh of battery capacity in excess of 4 kWh up to a maximum of $7500.


Car Payments

Car payments for each vehicle are made on an annual basis over 5 years.

Monthly lease payments are calculated as 1.5% of the MSRP.


Barrels of Oil Used

Vehicle barrels-of-oil use is estimated based on a vehicle’s use of gas and diesel. Oil used for the production of electricity is not considered.

Barrels of oil saved are calculated using the following formula:

= Gallon of Gas or Diesel used x (BTU per Gallon of Gas or Diesel / Well to Pump Efficiency of Gas or Diesel) / BTU per Barrel of Oil


Driving Profiles

The three driving profiles effectively weight PHEV annual fuel consumption and annual xEV electricity consumption. The consumptions are weighted by the percent charge sustaining and percent charge depleting. The first profile assumes 10% and 90%, the second assumes 40% and 60%, and the third assumes 80% and 20%.

[1] See EPRI’s ‘Comparing the Benefits and Impacts of Hybrid Electric Vehicle Options’ published in 2001, figure 4-8, as an example.

[2] Top 10 Best Selling Vehicles of 2008 based on U.S. News Rankings & Reviews:

http://usnews.rankingsandreviews.com/cars-trucks/daily-news/090107-The-Ten-Best-Selling-Vehicles-of-2008/

[3] Taken from the ANL GREET 1.8.

[4] Taken from the ANL GREET 1.8. Sheet: Electric, Lines: 15-29.

[5] Calculation based on ANL. GREET 1.8. Sheet: Vehicles. Line: 46 and GREET 2.8. Sheet: TEC Results.

[6] Calculation based on ANL. GREET 1.8. Sheet: Petroleum, Line: 191.