I recently drove from Long Island to PA, a distance of 220 miles. Since this was my first 200+ trip I drove at around 60 mph on the way to PA, and only used the a/c when it became warmer a little later in the day. The last 50 miles or so were done on secondary roads at about 40-45 mph.
The trip miles per kilowatt-hour showed 4.5, and I had 50 miles of range left according to the range meter.
The trip back was done at 60-65, with a/c on all the time, outside temps around 80, and I had almost identical results, although I did crawl across Staten Island in heavy traffic between the Goethels and Verrazano bridges, which probably helped with the overall range.
I agree with a previous reply that driving at 70+ will probably reduce range to around 200, but there are many variables on any trip such as terrain, weather, and traffic that will affect range, so there's no magic formula for an exact range estimate.
Around town here on Long Island my range is typically 250-275 miles, with a mix of local and highway driving.
I've been pleasantly surprised by the actual range I'm getting, although I'm sure winter range will be lower.
By the way, on my PA trip I charged overnight at a free level-2 J1772 at Millersville University, so my total energy cost for the 450 mile round-trip was about $10, as that's about what a full charge costs using my home charger.
So far I'm very happy with the Bolt's range and performance, and I had no issues with seat discomfort on a five hour drive without a break.