Highway driving

First time hybrid owner with a Prius C3 and about 500 miles under my belt so feel free to take these with a grain of salt. I am still trying to learn.

I had been experimenting with hypermiling during my daily commute (5 mi one way about ~20-30mph). My first week with the car I was at around 54 mpg (indicated) and I was naively trying to run on EV mode the most I can. Naturally the car was always battery starved. I since fixed that behavior with proper pulse and glide and more respect for the warm-up cycle and now I am around 60 mpg's with battery usually at 5-6 bars.

Today I finally had a chance to get some highway mileage on my new C3. We had a trip of 211 miles (me+2 passengers+a near full trunk). Mostly 55-60 mph, temperatures around 55-65 F, AC is always on and set to auto at 74F. The road has a lot of hills, a total roller coaster ride. On the first half of the trip, I switched off the ECO mode (The "perceived" feeling of pushing the car to go 55-60 mph all the time got old quick), no cruise control, tried slowly decelerating through the climbs and gliding in the declines. I must say that it is a lot of work and adjusting just the right amount of deceleration uphill to get to a target speed at the top is an art form that I couldn't master. All in all, I ended up getting a 57 mpg average.

On the way back, I was tired and lacked the focus. So I decided to try a new strategy:

1. Turn on the ECO mode.
2. Set cruise control to a minimum acceptable speed (I went back and forth between 55 and 60 mph depending on traffic).
3. After the CC is set, depress the accelerator slightly.

The result is 56.5 mpg. Pretty close to my manual work. IMHO, considering the two passengers, AC on, and not-broken-in car factors (my odo is at 600 mi now), not too bad. The trick is the step 3. It allows the car to accelerate during downhill glides. If you set the cruise control and keep your foot of the pedal, the car goes to regen in some downhill glides to keep the speed constant. A slight push on the pedal gets rid of that. ECO mode is on to:

a) Let the car do whatever tricks it does with the AC
b) Help modulate the slight application of the gas as I found I tended to increase my application of gas over time as my foot got tired I guess.

One note is, if you are on a flat stretch of highway, none of this matters. So just set the CC and foot of the pedal if you like.

 

Thanks, I am still trying to get to the 60 mpg mark. There I will be content as far as the hypermiling goes.

It is nice to know that you can still get that nice milage going at 70 mph. My experience is that you don't need cancel the cruise control at the top of the hill. Just push a little on the gas pedal, that will allow the car to accelerate (if the decline is steep enough) and not go into regen. I heard that the AC or open window tipping point is around 55 mph. That all depends on which windows you are opening by how much of course.