What exactly do you mean by ‘improvements’ to the internal combustion engine, to after market products and tyres?
For example, the IEA estimates that a package of low-cost efficiency measures, including variable valve timing for engines, low-rolling resistance tyres, efficient air conditioning and lighting systems, on-board fuel economy computers and displays (to promote ecodriving), and “stop-start” (idle-off) systems could together cut vehicle fuel use per kilometer by up to 20%.
