I wonder if the most economical solution would be to use the motor for regen on acceleration and then use the accumulated power for extending your coasting. That makes best use of the engine, which is more efficient under wider throttle openings.
I'm very impressed with your project. I've been keeping an eye on it as I plan to do something similar but with a Jeremy Clarkson bias! I'm looking at fitting something to my race car for a bit more grunt.
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