Honda already uses something like this in the engines for the 2006+ Civics:
Honda Worldwide | July 5, 2005 "Honda Develops New 1.8l i-VTEC Engine"
From the link:
"With the i-VTEC engine, however, intake valve closure timing is delayed to control the intake volume of the air-fuel mixture, allowing the throttle valve to remain wide open even under low-load conditions for a major reduction in pumping losses of up to 16%. Combined with comprehensive friction-reducing measures, this results in a significant increase in fuel efficiency for the engine itself."
It is a drive-by-wire engine, with the ECU taking care of throttle position, valve and spark timing, and exhaust gas recirculation to increase efficiency.
I have a 2008 Civic, and because of the different engine, I get better mileage with steady cruising than with P&G.