interesting history...gm was the first to look into varying the valve timing but scratched it in search of power from larger engines

fiat was the first to develop the precursor technology in the 70's offering it on several production cars - it was a simple hydraulic fulcrum system but was prone to malfunctioning

honda made the most significant leap and created a production worthy system - so well engineered there has not been a single warranty issue with its operation (honda's system switched between two camshaft lobes creating a torquey low end fuel efficient engine and a race bred high rpm high horsepower low displacement engine) - the dr jeckyl / mr hyde personality (most criticizm was lack of torque but these were always unfair comparisions as the vtec engines were always compared to larger displacement competition

honda developed 4 different systems too in the 80-90s (this doesn't even go into the i-vtec


bmw then made progress on the m50 e36 (m3) engine (bmw bought several honda cars with the worlds first vtec engines (b16a) and the nsx and studied it thoroughly...to implement it in inline engines was where bmw did their homework)...they first developed vanos which affected the intake side then double vanos which affected the exhaust side (the mechanical action was moving the fulcrum of the camshaft)

toyota also did what they could but focused instead on varying timing (which affected power and mileage to a lesser extent)

honda then mixed together cam timing and vtec to create i-vtec and we are just seeing the fruits of their labor (240hp 2.0 engines like the rsx type s - with a simple reflash)...with a 3rd evolution around the corner we should be seeing amazing technology