Prius C Fuel Efficiency Tips

I have to disagree with the pulse & glide technique in the video at the beginning of this thread. During the glide, the driver pressed the accelerator just enough to neither regenerate the battery nor engage the electric motor and coasted until the car slowed too much and then engaged the ICE to get back up to speed. This completely defeats the purpose of having the electric motor! The electric motor should be engaged during the glide as necessary to maintain speed and extend the glide as long as possible.

 

But that drains the battery faster, forcing you to recharge later. I personally would coast with no energy unless I knew I was going down a hill soon. There are some instances where extending the glide with EV would be better, mainly at <20MPH speeds. But don't take my word for it, try both ways a few times and see what results you get. With differences in traffic, terrain, and driving style, your way very well could be better for you.

 

Nyet, using battery power means you have to replace it. Keeping the battery high allows the electric engine to assist the ICE in acceleration, using less gas when accelerating. While using the battery can net you very nice MPGs, not using it can net you even more. Higher speed P&G is mostly on the ICE to get up to speed. If you are going to use the battery use it to get up to speed and go back into a coast until your speed drops again (P&G on the battery same as you would on the ICE).

That's not to say this is all real world practical (P&G on the battery), as the battery dramatically loses efficiency in acceleration the faster you get, with the mid to upper 20s (in MPH) being about all you'll get on level ground before wasting more power than it was worth to not switch to the ICE. So in back neighborhoods this is all well and good, but on the main streets you'll need the ICE, and even then P&G may not be an option in traffic.

 

I think you misunderstand what I'm saying. I'm not saying to pulse on the battery. The electric motor is just too weak for that. Pulse with the ICE lightly, keeping it out of the power zone. This actually charges the battery some. Then glide on the battery. Most roads(at least around here) won't allow you to glide long enough to completely drain the battery before you have to brake(regen) and accelerate(regen) again.

I did some shopping in Nashua yesterday. 35.4 miles of varied driving including a few miles on the highway. I got 68.1 MPGs.

Next time I'll try hard acceleration from every stop. Just seems counterintuitive to saving gas.

 

I disagree. Coasting is the best MPG you can get, which means pulsing to gain some speed, whether in EV or with the ICE it is more efficient than using the battery to hold speed. That being said, I frequently use the battery to hold speed because I'm often on 35 MPH roads in rush hour traffic, but that isn't the best MPG method. A Prius is a coasting monster, good aerodynamics, low roll resistance tires, and the ability to zero out engine breaking. At the lower end speeds the loss of speed on even level ground or better is a very slow process.

I don't suggest hard acceleration from stops, moderate acceleration to slightly over the speed limit, then coasting down to a reasonable level before starting it all over again.Whoops bad edit.

 

As a noob Prius owner this helped heaps. But there is quite a bit different from the c to the normal Prius I've noticed. Any other hints guys?

 

I just want to clarify that "coasting" doesn't mean keeping your foot off the gas pedal. If you do that then the car uses a little bit of regenerative braking which slows you down, which robs you of momentum and hurts fuel efficiency. "Coasting" means applying just enough pressure to the gas pedal to keep the "power graph" display in the position where it's not applying any power or any regenerative braking.

 

I think most people on PriusChat would say keeping your foot off the gas is "coasting". "Gliding" is when you apply enough pressure to the gas pedal to not apply power or regen braking.

 

I was responding to Fauxknight's post in which he said "Coasting is the best MPG you can get" - which is exactly why I tried to provide the clarification. But perhaps I should start to use "gliding" if that's the agreed-upon term.

 

I find it really difficult to find that sweet spot where I am not using battery/regen and not stare at the screen to get it to that spot.

 

I totally get what you're saying, but remember that the throttle position doesn't have to be perfect to be of benefit.

 

I want to share my "fuel economy success story" and bring up a relevant thread.

So, for the last year, my commute to one of my part-time jobs has been 7.8 miles and 18 minutes each way, with a section on the highway. Typically I get around low-50 mpg to work and low-60 mpg on the way back. But the highway is the only chance to pass and I get impatient drivers/tailgaters behind me, plus getting stuck at one annoying traffic light.

Today, I decided to try a new route that avoided the highway, and had a passing section on the backroad, but more hills and curves overall. The new route to/from work is 7.9 miles and 19 minutes each way. Based on today's trip, with a few minutes of mixed window/AC use, my fuel economy there was 61.3 mpg, and my fuel economy back was 75.5 mpg. I had to declare a spoken "WOW" for that. Oh, and I managed to keep the battery at 6 out of 8 bars at the end of the trip, so no cheating the battery either.

 

G'day,

A few thoughts/comments.

The opposite of the glide-coast situation discussed earlier could be the decision to "ride", or not, the brake lightly going downhill when the car already does apply some regeneration. A little "riding" lightly on the brake pedal to increase the default regeneration but not so heavy on the pedal to activate the old-fashioned friction brake.

And use to Sat-Nav to head toward traffic jams and away from motorways to save fuel - if you are not in a hurry, but turn the cabin air to recirculate .

And from recent experience, don't drive into headwinds or cross-winds on highways - I found my fuel consumption was up by 10% on a long south-west motorway trip with a very strong south-westerly blowing most of the way.

Not sure if these actually help in practice - just nice theories for an 'ideal world'.

David S.