The potential to achieve significant energy savings in the road transport sector can be a powerful driver to promote bus transport, especially bus rapid transit (BRT) development. This research introduces a spreadsheet tool for making realistic estimates of energy savings due to increased use of buses, with an explicit inclusion of the effect of congestion on traffic flow and fuel consumption. Based on scenarios developed around projected growth in trip demand, changes in vehicle technology, lane expansion, and modal distribution of trips, the model determines typical daily profiles for fuel consumption by vehicle types. A case study has been performed on an urban corridor in the city of Kuala Lumpur to compare energy usage among three scenarios: business as usual, conventional bus lane, and full-scale BRT implementation. The BRT provides significant energy savings over both alternatives, with the greatest savings achieved when locating the BRT in a newly constructed lane.