Toyota Yaris T Sport 2001

Toyota's Variable Valve Timing-intelligent (VVT-i) technology will play a key role in the development of T Sport products. It will allow Toyota to use more powerful, but lighter, engines across the T Sport range to offer extra performance and nimble, sports handling.

 By varying the overlap time between exhaust valve closing and intake valve opening, the VVT-i engine characteristics can be changed to create optimum burn - resulting in more efficient use of fuel, cleaner exhaust emission and increased torque output, particularly at low and medium engine speeds.The Toyota developed system has the benefit of offering continuously variable (not stepped) valve timing and allows the engine management computer to specify the optimum timing for the full range of driving conditions. It means the valve overlap timing no longer has to be fixed in advance to suit a predetermined driving environment.

 More complete combustion, at a higher combustion temperature, means less nitrogen oxide emissions. An increase in valve overlap results in some recycling of unburnt fuel which reduces unburnt hydrocarbons and also results in internal exhaust gas recirculation, further reducing nitrogen oxides.