There is an 8.9 stretch of road I like to take and try to get the best mileage possible in my cars. This is a pic of the best I got with the 2016 Prius 2. This is not a Prius 2 Eco. I drive this road several times a week. I do a lot of battery only driving, I coast a lot in neutral. The road is very curvy and lots of hills. The speed limit on the road is 50mph, I often reach 60mph while coasting in neutral.
If you had Prius Prime, then you could have had 999.9mpg easily. lol Oh, wait, if that was 2017 Prius Prime, then you would be limited to 199.9mpg. lol
Yes, knowing the elevation difference in essential. My old non-hybrid Subaru has beaten that for greater distances, though significant elevation descents were involved. One way to ensure a route with no net descent, is to do a round trip. A ScanGauge-II, such as in that Subaru, is limited to 9999 mpg. But since I reset its while stationary on a pullout, and had to use a few spoonfuls of gas to pull back out on the road, I think mine topped out around 2000 mpg.
Wind direction, too. A couple days ago, I drove my wife's '17 Prius 2 to a store about 6 miles away to the south with an elevation drop of maybe 15 feet. I got about 52 mpg going down there. Coming home I got 82 mpg. Some of the difference was cold engine warmup. Not that cold compared to many of you since it was about 75º here, but not insignificant. Much of the difference was the 15 mph wind from the south especially on the 50-55 mph stretch. Another huge difference on a trip that short is the battery SOC at the beginning and the end of the trip. In this case, it was fairly low when I left the house, fairly high when I got to the store, and fairly low when I got back home.
Starting elevation 1297 ft. Ending elevation 1104 ft. From East to West. 193 foot drop. Of course, there are many hills to climb and coast down. While I was plotting it out on Google Earth there was a graph that showed the elevations along the entire course. When I saved it, the graph is no longer available, as far as I can tell. I always try and have the battery full when I begin. Sometimes other drivers catch up to me and there is only two places they can pass, only one of them is a legal passing zone. One is around 6 miles(illegal) and the other is just after 7 miles. There are three places(right turn only lanes into neighborhoods) near the start where I can pull over and slow to a crawl to let others pass.
Thanks for that added detail. From my experience in my Gen3 Prii (originally a 2010, now a 2012), I've developed a crude rule of thumb that a gallon of fuel is worth about 10,000 feet of elevation in this car -- extra fuel required to climb, or saved fuel on descents gentle enough to need little or no engine braking. That assumes a light load, and throw on at least a +/-15% tolerance. From that rule, plus my better no-net-elevation-change performances over much greater distances, I figure that for my Gen3s to get the same figure on on a similar route (though won't display above 99.9) at 50-ish average mph, they need a 600 foot net descent. So you doing it with just under 200 feet of net descent is a very substantial improvement. Hill climbs and descents don't necessarily hurt mpg, if the driver is careful about energy management and the descents don't require much braking, or at least the energy wasting friction and engine braking. The Gen4's ability to glide much faster with the ICE not spinning is one of the improvements that significantly helps here. Because of my display limit, the best I could show for a much greater descent (with significant engine braking) is the pic on my media page showing it still pegged at 99.9 mpg at 80 miles, long after an initial 5000 foot descent was complete. A final bit of climb to home dropped it to just 91.3 at 100 miles.
are you talking about Prime ? because this is unbelievable. If it's the Gen 4 Prius, it doesn't drives more than couple of miles on EV only.
Unless you're going downhill. It doesn't take a very steep slope makes a huge difference over a few miles driving.
Is it too late for you to edit your post and take it out of the quote field so it looks like something you wrote?
If you're calculating in Imperial gallons though, that would be 4.5 litres compared to a US gallon at 3.8 litres so it would yield a higher number.
