I love cruise control, but will I do better without it?

I drive 46 miles each way to work, now mostly in the HOV lane of the expressway. I'm not a fan of going over 70, the most I'll EVER go is 73. I usually set my cruise control at 69 & roll with that but I don't think I'm getting the max MPG with this style of driving.
What's the best way to get the max MPG using cruise control?

I'm a noob- about three weeks old when it comes to the Prius. In my three weeks of falling in love with this beast I've found that cc is not effective if you are trying to maximize fuel economy and neither is driving above 60 MPH. If you REALLY want to kick some ass when it comes to fuel economy slow down and learn how to make pedal love to your car.

just my $.02

More details please. mpg? terrain? I don't use the cruise control because I believe I can do better.

Personally I stick the ECC at 55mph and leave it there for highway driving.

I don't need to be worrying about a couple extra MPGs when I have soccer moms in Excursions doing 75mph I need to avoid.

From the reading I've done here it seems that the difference is negligible between driving highway with the ECC or not.

http://priuschat.com/forums/knowled...ghway-driving-methods-toyota-nhw20-prius.html

The terrain of the Long Island Expressway (and most parts of Long Island) is pretty flat. At most, you'll get gradual mounds -- no hills, no mountains.

I think OP's question is: On a fairly flat terrain, what's the highway speed to set the cruise control to, that will produce the most MPG for the Prius?

You're right, I read his question hastily.

Basically, as slow as is safe. 55 is a good sounding number, and it works good for me.

Also, a lot of truckers (usually the owners of the truck) drive at 55 so I can draft safely behind them sometimes.

Eco-chic,

If you're willing to experiment yourself (e.g., for each of the next 6 work days during your highway commute, first set the cruise control to 70 mph, then go down 3 mph each day until you set it for 55 mph for the 6th day), I would love to hear your results.

I think I'll have to try taking Sunrise Hwy to work for this experiment. I'm pretty sure I'll get killed if I try to go slower than 60 in the HOV lane during rush hour :noidea:

Actually I use them as 'pace' vehicles and follow them at a safe, free from police interest, distance. The trucks are so massive that over taking traffic smoothly flows around the 'sucker stuck behind the truck' . . . and I'm laughing all the way to the pump.

Bob Wilson

My $.02. I use cruise all the time. Even when speed limit is 25mph I use cruise and get over 50mpg; usually 53.4 overall. When I am on I-95 I do the 70mph speed limit with the cruise. I get better mpg in the city than on the highway but as I said overall it is 53.4mpg for over 500miles on the odometer. Best I can tell you is to test with and without the Cruise Control and see what happens. Every car is a bit different. I do think that overall fuel economy will be better with cruise on.

I don't like using that soon-to-wear-out gas pedal when I don't have to, so I usually set the CC to the speed limit on ANY road as long as there's no traffic issue.

Highway is usually 63MPH and I'm passed no matter what the limit is...

Thank you for that.. As one of those who uses the HOV every day, drives me crazy when someone gets on there & does 55, while I'm stuck behind them & people in the main lanes are whizzing by.:boom:

i also use CC a lot and only have about 20% freeway. mostly surface at 35 mph... CC is convenient and easy, but yes you can do better with no using CC and feathering throttle, but if mostly flat and you minimal changes in traffic speed, then use CC, it take less concentration and the improvement wont be much.

CC hurts when you need to speed up and slow down a lot (even a few mph) or when there are a lot of changes in elevation.

from previous posts, sounds like its flat so we need to look at traffic density. when i am on freeway, i set CC at 62 and sit there in right lane. speed limit here is 60 anyway, but traffic is heavy so i am constantly adjusting speed with stalk up and down at 1 mph increments. takes a lot of concentration since speeds can drop to 40-45 mph (these are known slowdown areas) and worse.

so if traffic flowing well, i use CC because i can use concentration for passenger... if heavy, usually just foot it...

From what I noticed in my Prius, I tend to get poor fuel economy when using cruise ctrl. around the area I travel to and from work. The terrain has small hills and some short flat runs. I do well when I go downhill. As stated before, I may just use cruise only on flat highways. Perhaps once I take my car on a long trip, cruise may be my best friend to minimize driver fatigue.

Some people I know have a nervous gas foot. If your gas foot is more nervous than the cruise control, you are likely to get better mileage with cruise control.

That's my strategy too. I follow closely enough that people don't think I'm holding up traffic since I'm just stuck behind the truck. And I follow far enough that they can see that I'm not planning on passing anytime soon.

I use my CC every chance I get. For me it helps. Let me explain. I've tried Hyper-mileing a few times. But here in Seattle, I got the distinct impression that it was driving my fellow drivers nuts. And I wasn't seeing any real effect. Now it should be said that I bought my Prius in July. And by the time I got around to trying Hyper-mileing, it was getting into cooler weather. So the winter MPG losses may have eaten into it.

But I'm currently on my second tank over 450 miles at 54+ mpg, all while using cruise control. Here's where it's helped me.

Slower is better. I used to drive really fast, before I got my Prius. On certain roads, it's really hard to avoid creeping up in speed to match the 95+% of cars that are exceeding it. And a side benefit of this is that I never worry about speed traps anymore. I believe it's saved me at least two speeding tickets in the last 8 months!

But here's were I've had to adjust how I use CC. When going uphill I can see my low mpg. But for some reason, when I crest a hill, I can see that it takes some time for the car to sense that it can shut off the ICE. My solution is to cancel the CC just as I crest the hill. Then I watch for the mpg to shoot up. Then I re-engage the CC. That usually drops my speed by only 1 mph. After a few seconds on the downhill, I can tap up the CC to regain the lost speed.

And for those of you that wonder how I get that great mileage (or those others that wonder why mine seems so terrible..) I have a 20 mile commute each way. I've gone from using the freeway at 60 mph, to an arterial (that used to be the main N-S road) where the speed limit is between 35 & 45 mph most of the way. There is a small section that's 50 mph, and I hate it. (boy I never thought I'd be saying that! ha!) I can see the difference that extra 5 mph makes; especially if it's raining. There are a fair number of traffic lights onthis route. But I've gotten good at reading them, to know when to drop out of CC>

I used a modified cruise control strategy on rolling roads. When possible I down click the cruise on up hills when the MPG falls below 45 two or three times gradually and then up click the cruise on the proceeding down hill to make up the speed. This works the battery less and keep the MPG consistently above 45.

sounds like Old Hiway 99... ya, i take it a lot too. half the times, I-5 traffic much slower anyway.

Several times I’ve done a 200+ mile stretch non-stop on cruise control at 85 mph on that section of I-10 between Kerrville and El Paso, TX that has over 400 miles of legal 80 mph. The car is smooth and quiet unless it’s windy. On the straight stretches I average around 45-46 mpg. I-10 runs through part of the Texas hill country so there are intermittent climbing sections that hit the mpg; knocks it down to 41-42.

Here’s info on that stretch of I-10:

Texas: Home Of The 80 MPH Highway, 521 Miles Of Interstates In Rural Areas Now Have Highest Speed Limit In The Country - CBS News

The Prius gets the best mileage when pulse and gliding. That keeps the engine running in a more efficient power band. I have a rolling hill commute, so I just set my cruise control at 60mph and get about 53mpg.

If you have a flat commute you would do better at gradually speeding up to 65, then slowing down to 55 then rinse and repeat.

On totally flat terrain, I get around 48mpg at 60mph.