Keep the Chevy Volt in “Sport Mode”. The only difference is throttle position. In “Sport Mode” you have access to all the power if you need it, should be safer. If you do not need it, you can drive just as efficiently in “Sport Mode” as you can in “Normal Mode”.
In my opinion, Chevy should have made “Sport Mode” the “Normal Mode” and called “Normal Mode” the “Econo Mode”. The only thing “Normal Mode” is good for is when you are driving on ice or snow, although traction control takes care of that, so maybe only when you turn traction control off.