I took my first trip in my Prime into the Rocky Mountains. This and the return trip (right to left on the graph): The spike at the 60 mile mark isn't real. It's the Eisenhower tunnel so we actually went through the mountain (the spike) rather than over it. The car performed amazingly. First, it had no problems at all maintaining charge in Hv mode on 7% grades at 65mph. My 2004 wouldn't do that, rather it would drain the battery completely. Not the Prime. Start at 50%, end at 50%. Second, descending that huge hill from 63-70 on the way there (7% at 60mph the entire way) resulted in a gain of 30% on the battery. It looked like the maximum sustainable regeneration level was around 15kW, give or take a bit. It was dumping the rest into engine braking. Third, at the destination, we left the car outside all day starting at 28°F and ending at 11°F well after dark. When we got in, the battery was at 74% so I decided to put the car in charge mode to generate as much heat as possible by running the engine harder than idle. We had been outside in the cold for a couple of hours and wanted the heat. I got heat within the 60 seconds it took to get out of the parking lot, lots of heat within the three blocks it took to get to the highway, and a comfortable car within 3 miles - from 11°F! This was max everything - charge mode, no Eco mode or S-Flow on the HVAC, set-point at 74°F On the way back as an experiment, I tried to climb that really steep slope between about 70 and 63 miles in Ev mode. The car went up the hill easily at about 3/4 throttle for about 30% of the battery (75% to 45%). Then it tripped into running the engine. This was on a warm engine because of what I said above (charge mode). I expected it to trip earlier than that because that's a major climb, but it zipped up effortlessly in both Ev and after tripping into engine running mode (still in Ev). I left it the car in Ev from the top of the tunnel all the way home (that's from about the 63 mile mark back to the 0 mark). It used the engine on a few spots of big decent and on Floyd hill (30 mile mark) and the couple of the steep hills after. But I made it home easily all Ev aside from that. 63 miles starting from about 45%. I got home at 25%, without charging along the way. So, using 3/4 of one battery, a 162 mile trip resulted in 65.3mpg. Can't complain about that!
Very similar to my fall trip report. Mountain Driving Trip Report 66.8 mpg | PriusChat If one takes the time to think about maximizing the charge mode and maximizing the fun of driving up hill in EV mode this is a GREAT car to drive in the mountains.
This is why I am once again more content to have a hybrid with a bigger battery than the regular Prius.
I drove that highway one but not in my Prius, that is some mountain. Pikes peak would be another challenge. Electric cars are ideal for the Pikes Peak race because they don't suffer altitude sickness. lol
I've tested it but can't find any case where it makes sense: +90% EV - around town ~9% HV - when driving out of town <1% CHARGE - when low gas light comes on or I plan to leave later and want to use EV to reach cruise speed and then switch to HV Bob Wilson
Curious how hard you needed to be on the Go pedal on 7% grades at 65mph; was it into or beyond the PWR zone (pedal to the metal)?
I see. I guess even in cruise the power demand bar was probably high and the engine noise high? The reason I am wondering about it is this experience of mine: Anemic performance in the mountains | PriusChat
As others told you in that thread, you were being WAY too cautious. First of all, the bar gets to "PWR" at something like 1/4th of full-power. Maxing out the PWR red area is like 1/2 power. I don't know why Toyota chose this mapping, but when in the mountains, just forget it.
Well, it's because when you're on flats or downhills, sure, it can help you drive efficiently by keeping your pedal use restrained and the car loafing along. It's just really not practical to 'loaf' a 3,600 pound object uphill at high speed.
On these hills it will definitely be into the PWR bar in HV mode. In EV mode it never goes there. In EV Auto mode it might be able to with a warm engine, but I haven't tried it. Even when you reach the "top" of the PWR section, there is still more available, the car just doesn't show it. I have yet to find a situation where the Prime ran out of ability to accelerate. That is not the case with other cars I've owned. My 2007 Honda Civic (automatic) would have to shift from 2nd to 3rd around 65mph, and then the engine would drop to 3500 RPM, leaving it with no power to accelerate anymore. It would just cruise up these mountain passes at 65mph despite my foot being to the floor. If I somehow got a running start and kept it over 70, it probably could have maintained that speed. One time I had some extra load (a passenger and some bikes), and with the pedal to the floor the car slowed down from 65 to 45 before it decided to shift back to 2nd. I could have shifted it sooner, but I wanted to see what it would do. My 2007 4Runner V8 has the same problem when towing a 2000lb trailer in Colorado. Top speed ends up being around 65-70 going up these hills because of the gearing. I still got 15mpg on that trip. Having a CVT (even an electronic one) really is an advantage when you need to squeeze every bit of power out of a small engine. Maybe the electrical system in the eCVT would start to cut power after more than a few seconds of full throttle acceleration up a hill, but I've never needed to try it. Interestingly, even though the engine is rated at something like 95hp, I've never seen it go past about 50kW (about 68hp) on Hybrid Assistant. I wonder if that's because of the altitude or just a limitation of the hybrid system?
I once let my sister drive my Gen 1 and she was holding it around a steady 80 MPH going up Afton Mountain, which required a constant contribution from the battery the whole way, and I was just watching the state of charge on the ScanGauge counting down toward 40%. I knew at 39% she was going to immediately lose electrical assist and discover that a 71 HP gasoline engine by itself does not push you up a mountain at 80 MPH. But our exit came just as it was hitting 40%. My Gen 3, with the larger 98 HP engine, is able to take the same grade and even slightly charge the battery. It still definitely isn't loafing though.
Thanks. This pretty much matches what I saw on SGII (~2000RPM at the end of Eco zone, >2500RPM at the end of PWR and upto 5184RPM with pedal-to-the metal) on the 2020 Prime. I think aside from fuel economy concerns, the increased noise and sense of what sounds like a straining engine once into PWR and beyond is what makes most people (at least me) hesitate to go into PWR and beyond. Plus I was in the brake-in phase as well with the new car.
Since it has an eCVT, you can basically ignore the sound/RPM of the engine. It will optimize itself. You can run it at full throttle for extended periods if necessary.
At 10,000 feet elevation, air pressure is just under 70% of the pressure at sea level, corresponding to a max of about 65 hp. Down at 6,000 feet elevation, air pressure is just over 80%, corresponding to 76 hp.
About EV Auto mode: One route we drive is longer than the battery range and has some hills. A round trip here in EV Auto mode burns less gas than letting EV switch itself to HV. I think...for uphills the battery is drained rapidly; EV Auto runs the engine up these hills and saves battery power for the flats resulting in less gas consumption.
