Four Wheel Logic

To change a brake light, access the lamp housing, swap the bulb or unit, then test the pedal before driving.

Changing a turn signal bulb means accessing the light housing, swapping the old bulb for a matching new one, and testing the signal before you drive.

To change a key fob battery, open the shell, swap in the same coin cell, then close it firmly and test every button near your car.

To calculate your MPG, divide the miles you drove by the gallons of fuel you used and round the result to one decimal place.

To calculate monthly car payments, plug loan amount, rate, and term into the standard loan formula or use a car payment calculator.

To calculate miles per gallon, divide the miles you drive by the gallons of fuel your vehicle uses.

To calculate interest rate on a car loan, use your payment, term, and loan amount to solve the APR formula or check an amortization calculator.

To calculate fuel economy, divide the distance you drive by the fuel you use, usually shown as miles per gallon or kilometres per litre.

To calculate depreciation on a car, subtract its expected resale value from the purchase price and divide by the years of use.

To calculate APR on a car loan, you fold interest and lender fees into one yearly rate that shows the real cost of borrowing.