200 MPG Fish Tales

Copyright (c) 2009 PATENTWORKS LLC

Everybody knows; fishermen never lie about their catch. At times, they may embellish their stories just a little bit.

The automotive industry has discovered that customers can be enticed with high mileage figures. Media have joined the enthusiasm for energy saving cars. Suddenly we read mileage claims starting at 60 MPG all the way up to mind-boggling claims of 200 MPG to 300 MPG. Miles per gallon or MPG is supposed to be a number that car buyers can use with confidence to estimate future fuel and energy costs before purchasing a car.

GM recently announced that its new VOLT electric car will get 230 MPG. WOW!! How do we know how much is embellishment and how much is real?

First we must realize that the VOLT is a hybrid! When looking at driving costs, users must realize that they have to pay for energy in the form of electricity or gasoline. For the following comparisons it is assumed that electricity costs are $0.11 per kWh when plugged into a receptacle at home and that gasoline costs $2.50 per gallon at the pump.

GM has not yet stated how much gasoline and how much electricity the car consumes when driving 230 miles. We have to guess. A mileage figure of 230 MPG can only be achieved when the car uses only one gallon for driving 230 miles. GM tells us that the VOLT has a range of forty miles when using its batteries only. Media reports indicate that the VOLT will also have a 1.4 liter gasoline powered electric generator. Giving GM the benefit of the doubt, we can assume that the VOLT will achieve 50 MPG when driving on gasoline on the highway at 55 miles per hour.

Now we can calculate the mileage the VOLT can optimally achieve. The VOLT must drive 180 miles on its batteries and 50 miles on the highway on gasoline to get to the advertised mileage. Only in this best of all cases is it possible for the VOLT to use only one gallon of gasoline for driving 230 miles! In addition, the VOLT must be recharged at least once at home and four times at highway recharging stations when traveling 230 miles away from home.

GM says that the costs for driving the VOLT will be $2.75 per 100 miles at a cost of electricity of 11 cent per kWh. The comparable cost of energy from gasoline at 50 MPG would be $5.00 per 100 miles as long as gasoline costs $2.50 at the pump.

Recharging the VOLT's batteries on the highway will cost much more than 11 cent per kWh. (kWh is a unit for electric energy abbreviated from kilowatt hour). No refueling station owner can afford to buy expensive recharging equipment and provide multiple parking spaces for the time-consuming recharging process without a fair mark-up. Let us hope that the price of electricity at the highway recharging station is not more than 17 cents per kWh.

Recharging the VOLT's batteries with a storage capacity of 16 kWh will then cost $2.72 on the road. According to GM the VOLT can travel 40 miles on a fully charged battery. The cost for driving 100 miles will accordingly be $6.80. When driving on gasoline, the cost will be $10.00. The difference in driving costs per 100 miles will be $3.20.

After driving 100,000 miles the VOLT can save $3,200 in energy costs when driving on highways. The VOLT can save much more energy costs when only being recharged at home. The energy costs when driving exclusively on home delivered electricity will be $4.40 per 100 miles when using a 16 kWh battery and getting 40 miles per charge.

The calculated driving cost of $4.40 per 100 miles is considerably higher than the $2.75 per 100 miles cited by GM. It appears that GM has to explain the VOLT's performance more precisely.

More importantly, the announced mileage of 230 MPG is a fish tale and requires a very long, exhaustive, and complex explanation. It's a ruse to sell hybrids. Consumers have to insist on getting more easily understandable information for forecasting driving costs. The figure of 230 MPG is misleading!