For most commuters, a good benchmark for the cost of your daily commute is about $0.55 per km travelled.
This includes the cost of fuel, insurance and maintenance on your vehicle.

For example, if you drive to work 5 times a week and you live 20 km away from your office your commute cost is:

Travel distance = 40 km (return trip)
Days travelled per week = 5
Cost per km travelled = $0.55

Estimated Weekly Commute Costs = 40 km x 5 days per week x $0.55 per km travelled = $110 per week
Estimated Monthly Commute Costs = $110 per week x 4.33 weeks per month = $477 per month
Estimated Annual Commute Costs = $110 per week x 52 weeks = $5,720 annually