Does cruise control typically hurt MPG on Prius?

Toyota Engineers:

What cruise control needs is an "Eco Mode" that allows vehicle speed to decline up to 5 mph on inclines.

Toyota Marketing Department:
"The world's first cruise control with eco mode."

 

Why would you need radar? Wouldn't an inclinometer be simpler and cheaper?

 

I am curious. Wouldn't the car behind you be extremely pissed if you slow down on inclines? They would have to disengage their own cruise control. And if they chose to pass you, they wouldn't be able to once you suddenly begin to accelerate on downhills.

It's probably already irritating in local traffic, but most people expect speed changes there.

An empty highway is a different story.

 

if you're in the right lane, you have to expect speed changes with ramps, trucks and whatnot. cruise with radar would be perfect.

 

To be most effective, it would be useful for the car to be aware it was approaching a crest before it actually reaches the crest, so it can ease off the throttle before the top of the hill (and, ideally, be allowed to lose a little speed over the crest, picking it back up again on the other side).

 

Don't use the cruise control on hills.

 

Not really. Cruise control works fine on the right lane in light traffic conditions. Ramps and trucks require lane changes, not disengaging cruise control. You would accelerate to change lane and then fall back to cruise control. Changing speed to save gas makes matching speed with traffic flow far more difficult. It's also dangerous since most people would not expect sudden speed changes for no apparent reason, especially when the brake lights are not activated.

Cruising at the speed limit, while still irritating to other drivers, is a safer way to save on gas IMHO.

 

trying to drive in the right lane and switching lanes everytime you approach on/off ramps or slower vehicles sounds more dangerous to me.

 

In San Diego, on the I-15, there are five (5) lanes available for a long distance in each direction. I prefer to be in the #4 lane (counting from left to right) as I keep under the posted speed limit but also having to avoid the hassle of dealing with traffic coming on and off the freeway. I set the cruise control and leave it (Ron Popeil type operation: "Set it and forget it.") and I do fine with mileage.

 

Ford C-MAX already does something like that, it's called "Eco Cruise."

 

We have enough hills in western NC and I don't appear to get worse mpg when I'm on cruise. I get 46 to 48 mpg nearly always, cruise or not but then I have no interst in maximixing mpg. I always go as fast as I casn and that could be te difference.

 

Ah, ok.

 

....and engage their cruise missles

But I guess if they can make auto cruise control slow down when someone is in front, I guess it could also look backwards and hold speed if necessary

 

I wouldn't own a car without CC. With cruise, I don't have to worry about the cops.

 

i too have wondered this since I have a 71 mile trip to work, the interstate is mostly level but there are areas with some hills. when I get to the hills I normally switch off CC and maintain a constant throttle position versus constant speed.

On a side note I tried engaging CC when I was going 35 in auto EV mode and it didn't work, LOL. it turned the ICE on

 

CC will keep it in EV mode as long as you are on a flat or downhill... it won't if it needs throttle that is past the ECO line.

 

Just in general, you are better off not using CC as far as gas mileage AND wear and tear. I know most break in periods (5kish miles) say not use it. It controls through constant braking and acceleration, it can gage the driving conditions like you can. I'd avoid using it unless you just feel like you absolutely need to.

 

With a CVT, CC is ok as the CVT keeps the engine at different speeds even when going the same MPH.

 

That's why I was confused about why the manual recommended not driving at a constant speed for too long for the first 1,000 miles or something. Unless that has to do with something other than the engine.

 

The real question is: How much money does one save by using CC? And that answer depends on how many cops are patrolling the routes you take and the costs of a citation.

I drive my Prius to the workout club every morning around 5 am when the cops are waiting in prey, put the CC at 42 mph, and have not had a ticket in the last 10 years. More that offsets whatever increase in gas consumption it might cost.

CC is a Godsend and a necessary requirement for urban driving.