Nissan has produced a well know example of gamification in their Leaf line of electric vehicles. The 'Eco Mode' software keeps track of a number of variables (which are explained below) including speed and power usage and then provides constant feedback so drivers can improve upon efficiency. This feedback is provided by a display behind the steering wheel, which shows you your achievements through symbols which resemble needle trees. The car even provides online profiles so people can compete with other drivers, but there's no real benefit in collecting these trees other than saving battery charge.