Disappointing hwy MPG

One tip I have, turn Eco mode off when going above 62mph. It actually does make a huge difference, I stay steady at 63mpg while traveling 70mph currently. Also, using cruise control is not always best, the car seems to perform better when you accelerate quickly (without going into pwr mode) and then coast just above the ev/eco line.

2015 Prius C Model 3
59.8MPG Seattle Washington.
22,000 miles

 

Cruise is kind of your enemy in a hybrid, from what I've seen of the c's highway mpg it's pretty darn close to EPA numbers but only without using cruise. About 2-3 mpg difference. Also, the Mitsubishi Mirage delivers pretty poor interstate mpg, one YouTube reviewer achieved 32 mpg on the interstate.

 

I do not know, I found cruise was my friend. Well, we were at least cordial: it seems very good at achieving low mpg steady-state. Obviously can't anticipate slow down, use strategy, but other than that: I use it frequently.

 

Me too.
I find that the intense concentration required to do better than that just tires me out too quickly.

And I think some people are just fooling themselves thinking that they can do better than the computer does, if they really keep anything near to a steady speed.

 

I think this depends very much on where you drive. On flat, level ground I've found the cruise control to give me excellent fuel economy. But if you have any sort of undulating terrain then cruise will unnecessarily slow you on the downhills and require extra power on the uphills, which destroys fuel economy.

 

Cruise is good for relatively flat roads. If you have a lot of hills in your daily drive, even small ones, you can do better on your own. Although I have heard of something called adaptive cruise control which might be better, the CC in my 2012 C is the standard "set it and forget it" type which will do whatever it takes to maintain the speed you set, regardless of the terrain. The more efficient driving techniques I have learned since owning a Prius are second nature now and require no effort, so outdoing the cruise on my daily commute is easy.

 

Adaptive Cruise only keeps you from running into something ahead which is moving slower.
It "adapts" to the flow of traffic.

 

OK. Well that's a benefit, just not the one I was thinking of. I was imagining a truly intelligent computer controlled cruise. One that would allow you to set it for maximum gas mileage. It would adapt to changes in terrain by dropping back a mile per hour or two while going up hills, and allow you to coast to whatever speed you were comfortable with going down.

 

I agree! Level terrain it can sure help maintain a steady mph and help mpg be steady as well. Most of my driving is pretty hilly and I've tried using cruise but it seems to cut my mpg.

 

Pretty normal. When in my C unless I drive less than 68mph I will not get more than 45mpg... Tis why I have the '16 regular prius eco. Averaging 57.6 mpg over 12k miles almost all highway in that.

 

I can get away with going 55 mph on the highway. On my old 4x4 I would get 27 mpg at this speed. On my hybrid, I would get 57 mpg. Plus I don't cook the engine as much as RPM tends to stay near 1700.

Ford has that, it's called Eco-Cruise.

 

In our 50 degree weather and traveling 65 mph (cruise set) down to 55. And this is what it achieved. I'd try dropping your speed to maybe 72 next time your out on the interstate.