By Trevor Reichman

On Wa$ted, we're introduced to a family who is dependent on an unpractical vehicle. Their truck, which is hardly ever used as a truck, only gets 10 miles per gallon and is mostly used to transport one occupant to work and back.

Before you scoff, do you know the efficiency of your vehicle?

All cars come with a vehicle MPG rating, but there are many factors that aren't calculated in this estimate.

The best way to calculate your vehicle's mileage is to keep a trip log. It's easy and free

- Keep a notepad in your car at all times

- Whenever filling up your tank, notate the following, organized by date :

- The current odometer reading

- The amount of gallons used in the fill

- Cost of the fill ( if you want to also track what you are spending )

- Use subtraction and division to calculate your mileage. Subtract the current odometer reading from the starting odometer reading and divide those miles driven by the amount of gallons used. This will give you an accurate account of your car's MPG, rather than an estimate.

You can get a general idea of what mileage you are getting even after one fill up, if completely filling your tank. The gallons put into the tank are replacing the gallons used since your last fill.

Try to keep a trip log for at least a month in order to get the most accurate account of your car's efficiency over an extended period of time.

Keeping a permanent trip log doesn't take much time and can be extremely revealing, resulting in better choices and a greater understanding of what to look for in your next vehicle purchase.