Sounds like a Tesla would do you better with more EV range. Driving Volt's the past 3 years I can say that I do not need to use gasoline so all the gas i'm slugging around is just useless and worthless and could be more EV range.
Can't wait to upgrade my Volt to a Tesla after my lease is done!
Gas weighs about 6 lbs per gallon, much less than the equivalent 33.7kwh in lithium batteries. The ICE and associated engine-related hardware weigh several hundred pounds. If, as you stated, you do not currently need to use the Volt's ICE and burn any gas then any EV you would drive in the future with a range of more than your current Volt's EV range would mean you would instead be slugging around hundreds of pounds of expensive lithium batteries and not use the full range of the batteries. So it would appear to be a toss up as to how you want to package and carry extra fuel and range.