I live here in Colorado, and just moved from Boulder (north of Denver) down to the Springs. I've driven from Limon to Aspen, as far north as Steamboat Springs and as far south as Pueblo in my 2000 (green) Yellow Insight.

On the climb via I-70 from Denver to Genesee (the 'front range', not the continental divide) at 5-6% grades the battery runs down pretty fast and I end up in 3rd to keep up with the 60-65mph speed of the highway. The car will recharge almost completely on the coast down to Clear Creek (a 7% grade) and then I can stay in 4th until just about before Idaho Springs, at which point I have to go to 3rd to stay at 60-65mph with the IMA flipping between charge and boost depending on the grade (charging on the 4% climbs, boost on the 5% and higher inclines). I have to slow down to 50 in 2nd gear just before the Eisenhower tunnel (at about 12,000 ft above sea level).

Overall MPG for a round-trip between Boulder and Steamboat Springs - a whopping 68MPG, mostly acheived on the return leg coasting down from the Eisenhower tunnel to Denver.