A reader named Sam recently contacted me with a question about the poor highway mileage that he’s been getting with his new Highlander. He wrote:
“I purchased a 2015 Highlander AWD XLE two weeks ago and am looking for some gas-saving tips. The advertised mileage is supposed to be 18/24 (city/hwy) but I’ve been seeing 17 mpg on the highway. Are there any manual configurations that we can adjust to improve mileage, or anything like that? Other than this, I like the car. It’s drives smoothly, and there is no noise inside.”
Sam is correct that the rated mileage for an AWD Highlander is 18/24, with the FWD version doing slightly better at 19/25. So what’s the deal with him getting 17 mpg on the highway? That’s ca. 30% below the official rating!
Ways to improve mileage?
For starters, I don’t know of any manual adjustments that can be made, other than to your driving style. Jackrabbit starts and hard stops are the enemy of good gas mileage. But we’re talking about highway driving here, so that’s probably not it…
Another possible consideration would be the engine break-in period, which lasts for 600 or so miles. But even if mileage improves after that, I wouldn’t expect the break-in period to be the source of such a major mpg hit.
Or maybe the tires? I can’t see OEM tires, even a crappy set, knocking 30% off the highway mileage, but what about air pressure? Here again, low air pressure shouldn’t have that big of an effect unless the tires are wildly under-inflated. But it’s worth checking
Is he carrying around a ton of junk in the cargo area? I’m not sure, but the less weight you’re hauling around, the better your mileage will be. Here again, I can’t imagine any normal level of trunk junk having such a big effect.
So… I’m not really sure what to tell Sam.
With our FWD XLE, I usually see real-world performance that is within 1-2 mpg of the official EPA ratings. We get upwards of 24 mpg for pure highway driving (when steadily cruising in the 70-75 mph range) and somewhere in the 17-18 mpg range for pure city driving.
In reality, we drive on a mix of city streets, rural roads, and highways. The end result? On a typical tank, we’ll get somewhere in the 19-21 mpg range. Sometimes better, almost never worse. And the difference between the initial miles and those that occurred after the break-in period was negligible.
Given the above, something definitely seems amiss. If I were Sam, I’d head to the service department and discuss the problem with them. Hopefully, they’ll take his concerns seriously and help troubleshoot the problem vs. glad-handing him while they rushing him out the door.
What about you? Have you had problems with lower-than-expected mileage? If so, what have you done about it? And even if you haven’t, do you have any suggestions for Sam?