Though many of these commuter bikes aren't cheap, if you're giving up the car in favor of the most efficient form of transportation, you will of course save money. (metaefficient.com)
Their motto: the world's most efficient form of transport. (treehugger.com)
The ketogenic diet is a very low carbohydrate diet that allows the body to transform its source of fuel from glucose to a more efficient form of energy. (wellnessmama.com)