Does cruise control typically hurt MPG on Prius?

On the highway straight and level, cruise control does a good job. Up and down hills you can do better, and at lower speeds you can hypermile, but in general CC does a bit better than the common foot.

Tom

 

Re: The mileage - IMO, Yes - If you use the cruise, you ARE going to get worse gas mileage, especially if you are running up and down hills. NOW - if you drive nothing but flat ground, different story.

 

CC did better job then me on PA turnpike, and it is hilly. This is with 2 people + luggage in the car, not very loaded.

Generally in urban/extra-urban cycle I do better then CC.

 

Getting good highway mileage is a direct play between maintaining momentum while using the battery only at appropriately declining slopes.

What does "hurt" mean? What speeds and elevations are we talking about?

If you know how to drive a Prius to get good gas mileage, cruise control is a killer unless you're in an absolutely flat land. In the MD portion of I95 -which is rather hilly and suited for high speed (60-70 mph) Prius driving- my guess is that we're talking at least 5 mpg.

I used to cruise control a lot in the first three years I had the car, then I got a scangauge and saw the difference optimal driving makes in terms of mpg.

 

I think everyone who has responded has the same opinion. I think the real question is

1) How much impact does cruise control have in MPG loss vs manual control.

2) Is it worth the extra effort to do manual control?

I'm fortunate in that a lot of my commuting is relatively flat. Thus I use cruise control a lot. However, if I know I'm coming to a hill or sets of hills, I'll switch off the cruise control and "drive with load" (i.e. build up speed prior to reaching a hill, let the speed bleed off as I ascend the hill, and then glide to rebuild my speed as I'm descending the hill).

I guess you could say that I'm a "hybrid" driver in my use of cruise control.

I only use cruise control if I'm driving 50 mph or faster (highway/freeway driving).

 

how long before radar can 'see' the elevation changes and do a better job of anticipating hills and dales?

 

Now. But its gps and maps not radar, and its not in the prius. You do need a radar on the front and back to not impose on other drivers for speed variations. For prius drivers this is our eyes, but many ignore them

My guess is many that get much better mileage without cruise are actually going slower. The throttle is not easy to use to maintain speed. There is still some improvement at same average speed without cruise.

 

Trust me it really depends on terrain and traffic. If someone remembers to use the battery only on declines not throttle hard but maintain momentum overall everyone can do better than cruise control in hilly areas.

 

In moutain area, congested traffic, I don't use control but on most
interstate runs where road conditions are for the most part flat I use cruise control.

Cruise control is more comfortable after hours and hours of driving even if you take a small hit on mpg's its worth it on the foot / leg
discomfort without using it on long trips.

al

 

Couldn't you use cruise control and bump the speed down on inclines and then back up on descents? I did that with my RSX on hilly NV highways and did quite well--42mpg. I also turned the air conditioning off on inclines and back on for the downhills.

 

Had to agree with Afton on using cc on long trips. Another thing bout cc, it keeps you driving within legal speed limits and not having to watch the speedometer constantly.

 

Which is a useful thing in a CVT transmission car. You don't have engine noise to gauge how fast you are going. In my old Integra, I could tell how fast I was going by sound, I was usually within 2 mph of the indicated speed.

Every once in awhile, I forgot to shift into 5th gear, that would cause a expression on my face until I realized what I had done wrong.

 

You only need to look at nature; the human body. When bicyclists ride uphill, they slow down because it would take a massive amount of energy to speed up a hill. The human body naturally chooses the more efficient path; slow down when going uphill. When riding downhill, we get up to speed then relax and just let gravity do the work. On flatland, we put out a medium pace that we can maintain over a long period of time. Life would not survive if it was not a master at energy efficiency.

The most efficient is not constant speed (cruise control) but constant throttle position. Next time you are driving on flat terrain and come to a hill, maintain the same throttle position and observe how the car slows a little. Yes, it takes an extra few seconds to get to the top of that hill, but you'll still get there ... and you'll have more fuel remaining in your tank when you get to the top.

 

Congrats, way to go

 

Yeah, that is great; but watch out! I was applying your theory in Virginia on a trip with an underpowered rental car and got a ticket coming downhill, building up steam. Try and explain to "the man" that you were saving gas! LOL

 

I've driven that route many times. I put my Prius on CC and leave it for that sort of driving.

Tom