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Fuel Savings Calculator

Calculates fuel savings for 2 given mpg rates, miles driven and fuel costs.

This can be used to calculate if the extra cost of a more fuel efficient car (hybrid for example) can be offset by the fuel savings. With this calculator you can also calculate the breakeven gas price needed for the miles you plan to drive and the mpg (miles per gallon) of the alternatives.

cpg: The fuel costs per gallon.
miles: The miles driven.
mpg1: The miles per gallon for car #1.
mpg2: The miles per gallon for car #2.

Example 1

You are deciding between a conventional and hybrid version of a car.

The conventional car will lease for \$287 per month and get 22 mpg.

The hybrid version will lease for \$322 per month and get 40 mpg.

The lease is for 10,500 miles per year, or 875 miles per month. The current price of gas is \$3.79.

Calculate the monthly fuel savings and compare to the additional cost of \$35 per month.

Value Keystrokes Display Description
3.79 cpg 3.7900 Stores the fuel cost per gallon value.
875 miles 875.0000 Stores the miles driven value.
22 mpg1 22.0000 Stores the miles per gallon for car #1 value.
40 mpg2 40.0000 Stores the miles per gallon for car #2 value.
fs 67.8324 Calculates the fuel saving per month.

So you are paying an extra \$35 per month for a \$67.83 savings in fuel for a net savings of \$32.83.

Example 2

Calculate the breakeven gas price.

If gas prices drop, what is the breakeven price for the \$35 per month spent for the more fuel efficient car?

These keystrokes assume the values from example 1.

Value Keystrokes Display Description
35 fs 35.0000 Stores the fuel savings value.
cpg 1.9556 Calculates the fuel cost.

So \$1.95 is the breakeven for the extra \$35 spent for the more fuel efficient car. As long as gas stays above that price you will recoup the extra money spent.

Example 3

Calculate the breakeven gas price for 15,000 miles per year, or 1,250 miles per month.

These keystrokes assume the values from examples 1 and 2.

Value Keystrokes Display Description
1250 miles 1,250 Stores the miles driven value.
cpg 1.3689 Calculates the fuel cost.

So \$1.37 is the breakeven for the extra \$35 spent for the more fuel efficient car if you drive 1,250 miles per month.

In these examples I used the difference in the monthly cost of the lease since that takes into account the initial extra costs of the more fuel efficient car minus the additional value of the car and the end of the lease. If you are not leasing, be sure to take into account the increase in trade in value of the car and not just the extra cost of the more fuel efficient car.