Don wrote, in part, as a reply...
".....The car is very well engineered for what it was designed to do - A mostly urban commuter car with a 60 to 80 mile range. If that suits your needs, then buying an iMiEV is an excellent choice, IMO
If you need to go farther or faster, you should look into buying a car which has those capabilities, rather than trying to redesign something that was never intended for such use - A Chevy Volt sounds like the perfect car for what you want to do . . . . or maybe a plug in Prius..."
FWIW I completely agree with him.
I will add you might be very pleasantly surprised at how cheaply you can buy a used Volt that has come off lease.
https://www.truecar.com/used-cars-for-s ... =price_asc
And most of them will have very little age/wear on the internal combustion engine.
For example, one of my friends locally owns one and since she gets about 40 miles range on the plug-in batteries and 85% of her driving is within 40mile round trip with 30,000 miles and 3 years on the Volt there's probably not 8000 miles on the engine. If you find one with, say 80,000 miles on it keep in mind that there's likely way less than 80,000 on the engine.
The Volt is a well engineered plug-in hybrid with high performance and some clever features (such as the fact that, unlike our battery packs, IIRR if one cell in the main battery goes bad it can be replaced without replacing the whole battery pack. Ironic that the company that tried to kill the electric car did such a good job on the Volt.
And now, sadly, GM is going to discontinue making the Volt. IIRR the 2019 will be its last model year.