New Prius Owner Question - Cruise Control

Congrats on your car!

Opinion seems evenly divided between those who think the Prius cruise is the most economical and those who think their "foot sensitivity" will get slightly better MPG than the cruise. Overall, the cruise won't cause you to suffer decreased MPG more than 1 IMO.

Personally, I get out of cruise at the base of a long uphill climb so I can try to finesse it a little. But, like you, I never had it before my first Prius, and I still sometimes forget I have it. Sure takes the discomfort out of your right foot on a trip. Also makes me feel a bit silly just sitting there steering.

 

<div class='quotetop'>QUOTE(Zarzoo @ Jun 16 2006, 02:15 AM) [snapback]272091[/snapback]</div>

I too like c.c. - especially when there is a speed limit on roads where you tend to go too fast.

But I have wondered whether there is a safety factor: is there a danger of losing concentration slightly so that one finds oneself in a situation, perhaps a sharp bend, where the set speed is a bit too much? Has anyone else had doubts about the safety of using cc on long drives?

 

The c.c. implementation is indeed great and a nice way to prevent speed-drift. I don't generally have the sense that mileage is negatively impacted by cc.

One comment though: when I purchased my Prius (March, 2005), the salesperson recommended that I not use the c.c. for the first 600 miles. I'm not sure why he made this recommendation. My guess was that if you were to go up a long, steep hill, that it would require significant power output to maintain speed and it was better to avoid this during the initial break-in period. Most drivers not using CC would naturally let their speed drop a bit going uphill, requiring less power than the CC would keeping the speed nealy constant. I adhered to this recommendation, though I'm not sure it was that necessary. I have since used the CC going up a relativley steep hill a few times and the engine really screams, so it probably is best to avoid that, esp. initially.

Cool CC feature: I only recent discovered that the Prius CC has a nice feature that if you "tap" the up/down positions on the CC switch, the cruise speed will increment/decrement by exactly 1 mph. Often, this is an easier, faster, and more precise way to adjust speed during operation than just pressing and holding the switch until the desired new speed is reached. Want to increase speed by 3 mph? Tap it up 3 times...

Anyhow, congrads and enjoy cruising!

 

<div class='quotetop'>QUOTE(gmckee @ Jun 16 2006, 07:31 AM) [snapback]272133[/snapback]</div>

Actually, the recommendation was likely made to avoid driving at a constant speed, which is the primary no-no during the first 500 miles or so. The engine speed is supposed to be varied as much as possible during the break-in period.

I think the smoothness of the Prius cruise-control is more a by-product of the very smooth-shifting CVT than anything else. With a normal automatic transmission, the cruise-control will invariably force the transmission to abruptly kick-down to a lower gear while it tries to maintain a constant speed during heavy loads (mainly driving up grades). The Prius cruise-control will force the CVT to 'kick-down' under load conditions, too, but it's so smooth it's barely noticable.

Even with the CVT, if it's a particularly steep grade, the Prius engine will 'scream' if it really needs to gather speed so, as stated, it's not a bad idea to 'cancel' cruise-control and feather the throttle when those conditions arise.

As an added note, there seems to be two types of factory cruise-control switches. Lately, I've noticed some manufacturers (like Ford) forego the 'cancel' feature, forcing the driver to either tap the brakes or turn the cruise-control completely off to get it to disengage. It's annoying (to say the least) not to be able to 'cancel' without hitting the brakes or turning the cruise control completely off (which loses the speed setting), not to mention the safety hazard the 'cruise-control brake' causes by forcing following drivers to brake abruptly for no discernable reason, too. Then there's the added brake wear. You really wonder if the cost savings of omitting the 'cancel' feature is worth the driver aggravation it creates (and potential lost sales).

It reminds me a great deal of the early eighties when Ford, in anticipation of installing government-mandated airbags, thought it would be a great (and cheap) idea to move the horn switch from the steering wheel to the left turn-signal stalk. That idea didn't last long. Unfortunately, the cruise-control 'cancel' feature being omitted seems to be taking considerably longer to make a comeback.

 

Since we're talking about c.c...a word of caution.

DO NOT use c.c. when the roads are wet. If you begin to hydroplane the car will attempt to maintain speed, making matters worse.

 

<div class='quotetop'>QUOTE(rudiger @ Jun 16 2006, 08:54 AM) [snapback]272150[/snapback]</div>

Actually, the Prius has only one "gear" and it's not even variable. The engine is always directly connected to the front wheels with gears, even when in neutral. It never "shifts", "Kick-down", or changes gear ratios. It truely is completely different from any other transmission you might be familiar with.

Take a look at this site:

http://prius.ecrostech.com/original/PriusFrames.htm

Click on "Understanding the Prius" on the left, and then "Continuously Variable Transmission", "The Power Split Device", and "What's Going On As I Drive?". I found the "What's Going On As I Drive?" article to be the most useful one for me.

 

"Cool CC feature: I only recent discovered that the Prius CC has a nice feature that if you "tap" the up/down positions on the CC switch, the cruise speed will increment/decrement by exactly 1 mph."

I learned somthing new today.

Unfortunately, you can rarely [never] use cc around New York due to heavy traffic. After a few years driving in the New York area, you are ready for Nascar.

 

<div class='quotetop'>QUOTE(gmckee @ Jun 16 2006, 07:31 AM) [snapback]272133[/snapback]</div>

I use the "tap" feature all the time. In the 5 weeks I've owned my Prius, having traveled 2000 miles, I've learned to use CC whenever practical.

I set my initial speed to keep a safe following distance. As traffic slows, I tap down; as traffic speeds up, I tap up. If I need to slow down or speed up more than 1 or 2 mph, I hold the switch in the appropriate direction. When necessary, I'll pull forward to cancel.

I have found this easier to do than trying to feather the accelerator all the time. I just do that when driving in the city or on local suburban streets. On the highway (except in heavy traffic), it's CC all the way.

 

I think under most conditions I can get better mileage than the CC can, if I really pay attention. But on the highway I almost always use it because it's much easier and maintaining a steady speed is a good idea, it's what people expect and I don't like to "surprise" people. As previously noted it's not a good idea to use it when it is slippery.

At a safe driving course I took recently the instructor related the following: In areas where people tend to fall asleep while driving, long straight roads and not to much traffic, there is another phenomena. Apparently people tend to lift their foot as they fall asleep so without CC a lot of them go off the road at 30 or 40 MPH, with the CC set they go off the road at what ever speed they have it set at. I never drive when I feel I'm getting sleepy so for me it's not a factor but it is something to be aware of.

Here is something I discovered which is most likely more than you wanted to know:

I have seen one interesting thing which is unique to the CC on the prius and maybe other Toyota HSD vehicles. Going up a long steep mountain with the CC set at 65 or 70 MPH when the battery gets down to the last pink bar the car will enter a mode where it starts surging. Apparently what happens is the CC needs energy to keep the speed up so when it can't get any more help from the battery the engine will run at full speed as it should. But sometimes this puts a little energy back in the battery, when that happens the engine slows down and the little bit of energy that went to the battery is used up in just a second or two, then the engine increases to full speed again and the cycle starts over.

The best way I found to deal with it is just to turn the CC off and slow down 10 MPH or so. I don't consider it a problem, just something interesting. Also conditions need to be just right for it to happen, for example U.S. Highway 50 going across Nevada has steep high mountain passes and a 70 MPH speed limit and I observed it several times. I have never seen it here in Eastern Oregon, our mountains are just not steep or high enough.

Has anyone else seen this?

 

As a practical matter, the cruise control provides me better mileage when I am on the freeway/highway. Long distant travel can wear down even the best of feet.

Enjoy the Prius cruise control. It will serve you well and provide you good mileage at the same time. It may not be the absolute best but I believe you will be very happy with the results.

Cheers

 

The Prius CC is nice and on the freeway can help you maintain speed. Use caution in heavy traffic.

Always pay attention though. In a severe situation, your first reaction is to take your foot off of the gas, which can buy you reaction time. In cruse control mode, you lose that time.

CC is cool - but be safe, fellow Prians

 

Does anyone else find it odd that on a steep downhill the cc won't force regeneration to maintain speed? I made a trip to Pittsburgh a couple of weeks ago and was really surprised to find the car gaining speed on steep downhill highway stretches around town. I just assumed the cc would use regenerative braking to maintain speed, but it didn't. Best it could do was glide, and before long I was 5 mph or more over the set speed and had to brake manually.

Geoff

 

<div class='quotetop'>QUOTE(Jim1eye @ Jun 16 2006, 09:06 AM) [snapback]272153[/snapback]</div>

This is less of an issue with the Prius, since it has traction control and will automatically slow down if the wheels lose traction. If you have a model with VSC, then that will kick in, even if you are on cruise control.

Tom

 

After 5700 miles, with about half of that on the highway, I don't see much of a decrease in mileage using the cruise control. If anything it can help keep your speed from increasing to the inefficient speeds of much of the traffic on the highway.

 

I use cc whenever possible, I love the uniform speed it provides and the relief from worry about getting a radar generated speeding ticket. The Prius cc is extremely accurate and does not drift away from the set speed as much as other cc equiped vehicles I have owned.
Living in Florida, with very few hills, with cc set on the highways and driving the speed limit, I always get the epa listed 50 mpg or better.
That said, I do not like the little stick control Toyota uses to activate and control cc settings. GM also uses the controls mounted on a stick but Ford and Chrysler have buttons on the steering wheel. (sorry not familiar with European or other Japanese models). I have found that I have to take my eyes off the road to remind myself which direction to pull the stick to make the adjustments whereas the button activated controls can be done by touch.
I also do not like the loss of speed setting memory when your speed falls below 25 mph. All other cc equiped vehicles, I have owned, retained the last speed setting until either the cancel function was activated or the engine was turned off. (did they change this for the 2006 Prius?)
And finally I do not like the placement of the cc stick. I am 6'2" and if I exit the vehicle with the wheel slightly turned to the right, with the cc in about the 5:00 o'clock position, my knee will strike it.
I find cc to be required accessory for any car I buy.