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Discussion Starter · #1 ·
8)
I just passed the 1,000 mile mark. I am averaging 48.3 MPG. Best
trip MPG = 60, worst trip MPG = 41. The one thing I can't figure out is that I get 3 MPG less when I use CC. When I first observed this, I thought I had miscalculated so I ran the same 60 trip again. I run this trip several times a week, so I have good records. 60 miles, several long hills, SoCal, Shell gas, outside temp: about 65, tires 37/35, speed 65. I can normally get 49 to 50.3 MPG without CC. With the CC on I get 46. I guess my question is, will using CC normally cut your MPG?

Fred
 

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CC is most effective on level stretches. It does a better job than most in modulating your power. CC is lousy in up and down terrain. It over revs, then tries to slow you down, then over revs, ad nauseum.
 

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cc can't anticipate what's ahead. you can.

going up a hill, you can slow down a bit and try to coast up. cc will do its best to keep you at the set limit.

i usually do better than cc, so i only use it on long trips.
 

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I would also suggest inflating your treds to 42/40. It's a common personal setting but is highly popular in the get-better-mileage department.
 

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I don't think CC is doing anything wrong, it is doing its job, which is to keep your speed constant.
However, if you drive 'manually', you can allow more leeway in your speed, thus providing more coasting opportunities than CC would let you.

Think of a roller-coaster. Energy is put into the system only on the initial climb. Engineering uses gravity the whole way, with the lowest point being the fastest, but the speed of the cars vary with height. Imagine what would have to be done energywise if the roller-coaster cars were required to keep a constant speed!
 

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River: Is your 60 mi trip on I-5 or heading east into the hills..?
On the level freeway I can't beat CC with my foot. I get around 50 mpg to/from OC using cruise at 65 MPH. But on long climbs into the desert, the foot (and ear) has better sensitivity to ICE sounds which translates into MPG. I don't think you have a malfunction. It seems you have a choice to make between max mpg or the relaxation of auto pilot.
** BTW; If we get all the rain that's forecast, you'll be safer with the tires below 40 psi. I normally run 42/40 but will bleed em down if it rains real hard. (Personal opinion based on rudementary physics) ~JD~
 

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Discussion Starter · #7 ·
JD,

My daily run is between Escondido and Mission Valley via Rt 15. Lots of long hills and bumper to bumper traffic on the way home. I do not believe there is a malfunction with the CC.

I've been keeping my tire psi at 39/37. If it rains tonight, I will drop the psi to 35/33 and see how it handles in the rain.

Thanks for the advice.

Fred 8)
 

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I have a short commute from La Lesa into South Park. I am being really good and staying about 65-70 on the 94 but my smaller jaunts in the east county hillsides keep my mileage around 43mpg. I did get upper 40's on my last trip to Paso but that was early into my ownership and I am sure that I was not using the car right at that time. I too find that foot control is often better than cruise control, especially in the hills.
 

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I just made a trip from Denver to Sedona and back. I'm guessing I was using CC for 90% of the time and averaged 46mpg with a wife, 2 kids and a bunch of stuff in the back. At one point through New Mexico after a fill up, I was getting 52mpg for about 200 miles doing 80 with the CC. On my daily commute, if I use CC and stay under 65 I can easily average in the mid 50's. So I guess you could say I am now a fan of CC. Thanks,
 

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My CruiseControl does a good job, even in the Texas "Hill Country" when I visit that area. Dallas is pretty flat for the most part and I use the C.C. even around town. I do find it quite agressive and am likely confusing other cars on the road going uphill. In an "ordinary" car it's probably human nature to slow a little going uphill and accellerate a little going downhill. I find myself passing "ordinary" cars uphill and them passing me downhill due to the accuracy of the Prius C.C. [[SIGH]]

N.Y. Day, cruise set to 75 MPH, all freeway, I got 54.5 MPG - on cruise control most all the way.
 
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