Interestingly, Honda, who are the recognised leaders of Variable Valve Timing technology (never had a failure; ever) did not take the approach of a smooth transition on their latest VFR motorcycle, and have now received criticism for the abrupt increase in power as the timing changes, suprising many riders! Also, in top gear, the VVT engine is cycling (no pun) between using advanced valve timing or not, all at legal cruising speeds.
probably not so obvious or problem with the weight and momentum of a car, but on a bike, a big issue.
I havn't got a VFR by the way (Honda Blackbird + Supra (of course!))
Tony