The one thing a CVT has going for it is the "constant". Trying to force the belt manually isn't going to help efficiency or performance. They are already load sensitive so you can set it up to cruise at low speeds at the torque peak and yet, rev up to the power peak when you pin the throttle for max accel.
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The problems which reduce efficiency versus a chain and trans are belt losses from bending as it goes around the pulleys. And compression as it goes between the pulleys. Also CVT's don't have quite as much range as a 6 speed trans so the highway speed cruise rpm is topped out in ratio and well above the torque peak unless you give up accel from launch with longer final gearing.
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Also for hypermilers, on a CVT there is no way to PulseNGlide as you would be able to on a bike with a hand clutch.
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But there are some CVT scooters doing some good numbers and the CVT takes the driver gear selection out of the equation. Everyone on a Honda PCX can get a really high fuel efficiency of 94 mpgUS depending on how aero you are on the bike and the average speed. A geared bike like the Honda CBR250R has more variation since many traditionally schooled sport bike riders choose to ride around at 45 mph all the time in a gear that is near the power peak so they can have max accel without shifting to "get out of trouble" and end up with 60 mpgUS. Whereas I can take the same bike and putt around at 45 mph/ 4,000 rpm in competition using pulse and glide with engine off coasting and get 135 mpgUS.
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