They'd have to be shorter than 400 miles to be safe. At which point, it's probably just as fast to drive (or faster, given it's a prop plane whose speeds are in the ~200mph range).
My GF's sister lives in central Nebraska. 300 miles from Denver, 120 miles from Omaha. An electric airplane with 600 miles range would be 'fine'. Driving would cost about $150 when you include fuel, maintence, and depreciation.
