I’ve had a fascinating experience with my Toyota Prius in the last few months and am curious whether other Prius or hybrid owners have experienced similar: The Prius gets significantly better mileage in lower altitudes.
Here’s the scoop: I live in Boulder, Colorado, at approximately 5300 feet elevation (just a smidge higher up than Denver, the “mile high city”) and on average, we see about 39MPG driving our Prius around in town and occasionally to Denver or the Denver International Airport. Not too impressive and a far cry from the 60MPG that Toyota claims in its advertising.
I’ve even taken the car in to Toyota for a checkup. They’ve run a full set of diagnostics, checked all the firmware and applied all the latest patches, etc., but there was nothing they could find that indicated anything out of the norm. Their great solution? We were driving it in a way that was adversely impacting our mileage.
However, I have spent most of June and July at the Lake of the Ozarks in mid-Missouri, altitude approximately 900 feet above sea level, and guess what?
We’re seeing approximately 46MPG on average for a tank of gas, even with the hills in Missouri (lots of rolling hills), the greater load than usual (in Boulder its usually a driver-only vehicle, in Missouri we’ve had the kids in the car most of the time), the same two drivers (my wife and I) and roughly similar road conditions.
I thought that perhaps it was the octane level of the gas, because in Colorado we have lower than normal octane because of our higher altitude. That might be a factor: I’m going to experiment with using mid-range gas now that I’m back in Colorado, but I’d be surprised if the octane level would make a difference and I certainly haven’t ever seen anything to that effect when I’ve poked around online.
Therefore, the only other possibility I can imagine is the altitude.
But how can that be? How can a difference of 5000 feet of altitude impact the Prius so much that our mileage drops from 46MPG to 39MPG on average?
Have any of you fellow Prius or hybrid owners heard of anything like this before? Is there something I can do to tweak our 2004 Prius (first year of the second generation design) so that the fuel mix / carb / fuel injection / whatever is optimized for our higher altitude?
I was shocked by the difference, quite frankly, and really wonder whether this doesn’t point to a significant limitation with hybrid vehicles in Colorado and other high-altitude areas too.