A few weeks ago, a man named ’Don Parsons of Denver, Colorado’ took his Charge-point EVSE where his i3 REx accepted 8.9kWh’s of juice to help with the rest of the climb up the mountain. The car showed 18 miles remaining at the top of Loveland Pass, and he nearly made the trip entirely on electricity when 62 miles later the range extender kicked on and he was only 2 miles from his home.-64 miles each way
-8,960 feet of climbing, 2329 Feet of descending on way out
-2329 feet of climbing, 8,960 feet of descending on way back
His next challenge was to take his i3 REx up to the summit of Mt Evans which is the highest elevation in the US. The trip would take him over 14,000 feet above sea level and would most certainly push the range extender beyond its limit. This was not the kind of road trip BMW envisioned people taking the car on when they designed the REx, but nonetheless they have to expect some people like Don would do just that.
After his trip up Mt Evens, Don wrote about his day! Want to hear what he had to say? Keep reading…
“I've had my BMW i3 REx for almost two months now and haven’t really used or tested the REx engine. Before today, I’d driven about 1750 miles total with only about 10 miles using the engine. I decided to drive from my house in Denver to the top of Mt. Evans and return without stopping for gas or topping off the charge. Using the REx engine in the mountains can be tough because the output of the small engine can’t really put out enough power to go both highway speeds and climb uphill. However, the road to the top of Mt. Evans is pretty narrow, has steep drop-off's, no guardrails and a lot of cyclists sharing the road so you really don’t want to go much faster than 35 mph. For this reason, I thought the small engine could hopefully handle the climb.
I set the car into Eco Pro+ and set out on city streets of Denver, then I-70 west up the mountains to Idaho Springs. Mt. Evans highway winds its way south from Idaho Springs to the Mt. Evans summit in 28 miles. When I originally entered the destination into the navigation system, the guess-o-meter said 61 miles of range. I tried to keep the cruise control set to about 5 miles over the speed limit.
I could hear the engine speed up during the straight parts of the switchbacks and as I slowed down for the sharp curves, the engine almost immediately slowed down as well. I never really wanted to travel faster than 35 mph so I didn't notice any performance hit until near the summit. On the last few switchbacks, I put my foot to the floor and couldn't get the car to travel faster than 26 mph. At close to 14,000 feet of elevation, the engine was probably severely limited from its usual output at sea-level. I've heard people say that an ICE reduces power output by 5% for each 1,000 feet of elevation. In any event no other cars were travelling any faster than 25 or 30 mph so I didn't feel unsafe.
During the descent from the summit down to Idaho Springs I was excited to see that the regen had built up a full 25% of the battery SOC and the guess-o-meter said as high as 28 miles of range on the battery. I drove home significantly on battery but the REx kicked in a few times where there was some climbing. It also stayed on once I got out of the mountains but I was easily able to maintain 75 mph on the highway leading east back into the city.