Just bought a 2008 Prius - Package II. I used to own a 2003 BMW M3.
I love the Prius, right now I am getting 47MPG average (16MPG with the M3). I inflated the tires to 40PSI front and back and learning to drive with a lot of cruise control.

 

Congrats, myhybrid, on the new Prius, and I'm glad you love it so far. Welcome to the forum! Proper tire inflation is a very good idea for getting the best mileage out of your hybrid, but driving with a lot of cruise control is not actually the optimal technique. I can see how it might be an improvement over the way some people normally drive- all that energy wasted by constantly changing speeds, stopping, starting, trying to get around other cars on the road, being a road hog- but people who are trying to drive for high gas mileage can do a lot better themselves than the cruise control can do for you. The point isn't so much to maintain exactly the same speed at all times (modifying your speed when you go over a hill, for instance, can conserve your gas efficiency much better than trying to maintain the same speed) as it is to minimize lost momentum or wasted energy.

Take a look around the forum and you can pick up plenty of tips on how to get better mileage than cruise control will get you. In the meantime, good luck, and good job for getting 47 so far- that's a great start.

 

As good a moment to bimble into the forums as any. Your post is interesting Leah, as I've recently had a Prius T4 on trial (have now ordered one).

My current vehicle is a Peugoet 307 SE SW 2.0 litre diesel and it definitely drives with more economy in cruise control. I have run the same motorway trip, for example, in the same weather and at the same speed in manual and cruise and had an improvement of 5mpg in the latter. I currently get a (measured over 78,000 miles, not via trip computer) 49mpg from the Pug.

In the Prius it quickly became obvious that cruise knocked about 5mpg off the economy. That's a shame since I like to run on cruise, even at low speeds, and I now need to master this hyper-whatsit thing you all go on about! (I was getting about 58mpg in my trials overall - UK gallons of course).

 

Hi,
Welcome to the forum and when you get the car, we'll welcome you to the club.

I am curious about your 5 mpg (Imperial) hit on cruise control. Could you give a few more specifics?
- end points and route (we can use Google Earth to look at the terrain)
- speeds (metric or real)
- how the mpg (Imperial) was measured

We know on hilly terrain that high speed cruise control hurts because it puts the ICE in inefficient, high rpm ranges. By slacking off the speed when going up a hill and catching up on the downgrade, we can achieve excellent cross-country speeds and efficiencies.

Thanks,
Bob Wilson

 

Thanks for your comments Bob. Since I had the trial Prius only three days I managed insufficient mileage for a real economy evaluation (about 250 miles). Gloucestershire is wonderfully hilly; not mountainous but certainly not flat. Once I have the new motor in the New Year and join, as you say, the club I will collect valid data over time. And learn to work with the terrain.

 

Actually I live in the souther california suburb. Mostly flat roads. Using cruise control has helped me, here's what I do:
I accelerate to the speed limit while release the gas pedal, then when I hit the speed limit, I set to cruise control, most of the drive is handled by the electric motor.

What helped me though, is inflating my tires to 40/40 and filling up half of the tank. I am now getting 52MPG city and 54 MPG highway (driving 65MPH).

 

Bish, welcome to the forum. Sounds to me as if you might already be using fairly good driving techniques if your cruise control was doing worse on the three days you had the Prius than you were doing on your own, but there are some things about being used to driving with cruise control that can help you learn good hypermiling techniques. For instance, trying to maintain a constant speed is actually quite energy efficient on flat ground with no stopping and starting- just going around obstacles and curves at the same speed carries your momentum with you and keeps your energy use to a minimum.

However, even in places that you think are fairly flat (I live in a midwestern plains state where we practically invented the term flat) there are a surprising number of ups and downs built into our roadways that really do make more of an energy difference than you would expect. Everything from overpasses to onramps can be enough of an incline to need a speed adjustment, and keeping a feather-light foot on the pedal to finesse the least energy loss or the most retention of momentum is the essence of being an efficient driver. If I turned over all that control to a cruise-control system, I'm sure I'd be frustrated at the wasted energy.

 

I agree,

I used to use cruise control (which was better than my previous driving method), I got 46MPG combined. Now that I use my foot, I get 53MPG combined. It's a skill that can be attained fairly easy, the trick is to relax your foot and not be tense, let the weight of your leg do the work.

You will notice that you won't get the fluctuation 99.9 MPG to 30MPG you get with cruise control, rather you will get fluctuation between 77MPG and 50MPG which will yield better gas mileage. You can even accelerate in a downhill while staying above 40MPG, this will give you the momentum you need going uphill while slowly decelerating yet still achieving above 30MPG, on the way down of course, let go so you can recahrge your batteries and get maximum mileage.

 

I have had my Prius a month now and would suggest using CC as much as you can until you 'learn' how to maximize your milage using the tips found here.

Just my .02

 

The way I like to put it is this:

Drive like a truck.

It's not really about the mechanism of cruise control, so much. It's more about maintaining speed when possible to avoid wasting energy. Compared to cars, huge trucks take longer to get up to speed, and they spend a longer time braking and give themselves plenty of room to slow down. Once they get moving, they keep going, all that momentum moving forward, and try to coast through bits of slower traffic with a bigger buffer in front of them so that they don't have to put on the brakes. These are the things you should be doing in any other car, too, to save gas. Try it! Drive like a truck!