List of ways to improve fuel economy?

Hi there,

My parents still live in Berkeley and have a '04 Prius (no roof rack). They average in the mid 40's. My dad says he doesn't so anything "special" in the way of driving, except for having a lighter foot.

Just remember that short trips are FE killers. Can you "batch" errands, going to the place that's the most distant first and then working back to your residence?

The other thing you can do is look at your routes. For instance, my parents will drive down the steep part of Marin in the Prius, but they always go back up the hill on streets with more gentle grades. I know that may be a bit an extreme example, but it should certainly illustrate the point.

I don't really think that you're going to find a mechanical answer to this, but you might find answers in looking at how you're driving.

 

How fast do you go on the beach trips? The roof rack may be hurting even more than you think.

Do you ever shift into "B"?

 

It takes some time to get used to but eventually you figure it out. Getting better MPG that is.

I was stuck in the mid-high 40s for a very long time. I even complained about how I could not get better milage even though I tried P&G and other little tricks. Eventually I started to master the throttle control and now I can get 60mpg tanks if I alter my route and try hard to max mpg. If I don't try hard, use normal routes and drive the speed limit I end up with 49-53mpg. So there may be hope for you unless you just have a terrible route.

One thing i notice myself doing that the average drive may not do is to accelerate up to the posted speed limit fairly briskly then let off the pedal fully then reapply lighter pressure. Now I realize most PriusChat people do this but your average Joe probably does not. Once you realize the difference this makes you start noticing other instances where lifting off the throttle then reapplying pedal can change your instant mpg by 10-20mpg quickly. In this instance you are simply changing the amount of time you sit at say 23mpg before you transition to say 50mpg. I see this alot on city streets where the speed limit is around 40mph and if you accelerate like a normal car and do not do the "throttle lift/reapply" trick the MFD will sit right around 40mpg or so and slowly raise up to 50+mpg (like it should be at 40mph). Maybe this doesn't play as large a part in efficiency as i think it does but it surely cannot hurt.

Gliding whenever possible is the largest producer of big numbers for me. I can drive like the average Joe most of the time but if I throw in a bunch of nice long glides my MPG shoots right up.

 

I live in the bay area. My tank avgs are 51-52. My tires are 35/33, I don't like the harsher ride. I usually have the MFD off, but use the graph screen to check totals at times. I do better with feel. Back off as much as possible on the gas pedal, like there is an egg under the foot. Slow down to 62 or less on the freeway. Back off the gas at 60-62 and the engine really goes low in rpm, silent it seems. I get 52-54 on level freeways at that speed. I disagree with others about brisk acceleration. I have tried it that way on the same course, and it uses more fuel. The owners manual also tells to accelerate gently. Drive like the little old lady from Pasadena. The gas pedal is very very sensitive on the Prius. Check the engine air filter and make sure it is not clogged. Driving in traffic 30-35 mph, I am seeing higher mpgs. At 50 mph with lots of stoplights and accelerations I see the lowest mpgs about 50 or just under. Moderately brake as much and long as possible, not just coast, when coming to a stop. Just hard enough not to annoy the SUV three feet behind. That roof rack may be some of the answer. My 51-52 avg includes lots of cold start, short trips, driveway moving where the engine starts for nothing, and the like. I rarely drive more than 6 miles per restart. That's my list.

 

1) Slow down on the freeway. Try not to exceed 65 mph, 60 mph is even better. You won't save that much time driving 70 mph vs 60 mph.

2) If you can, take off the roof rack for a tank or 2. (reset your mileage) and see if you note a difference. I don't know how easy it is or is not to remove and put back your roof rack, but try it if you have the time and the effort isn't too great.

 

My best advice is to not concentrate on miles per gallon, but concentrate totally on *gallons*.

What's better:
1. Getting 50 mpg during a month of driving, and using 10 gallons (500 miles of driving) for that month...
or
2. Getting 40 mpg during a month of driving, and using 5 gallons (200 miles of driving) for that month?

When we concentrate on the mpg, we sell ourselves short. We should be bragging about how much we didn't drive. About how much gas we didn't burn. Instead, the emphasis is on mpg - and for many, that means driving MORE miles, and burning MORE gas so that number looks better.

Might not be the case with you... but if you just concentrate on NOT driving the car so much, it really doesn't matter what your mileage is when you DO drive it. For the short trips around town - ride your bike. I managed to live in Berkeley for several years without even owning a car. I even had a girlfriend way up in the North hills!

 

The best advice yet!

 

You're welcome. Believe me, I understand the envy thing, my parents even express that.

I think that some of the differences are terrain and other driving conditions. I know that west Berkeley doesn't have any extreme hills, but I promise you, you've got more terrain that we do here. I also know that I'm learning to see the very gentle terrain that we've got and make appropriate gas peddle adjustments.

Even driving here, it's very easy to give the Prius more peddle than is actually necessary to maintain a desired speed. That's another FE killer because gas is being burned to no effect other than spinning the ICE. It's one of the reasons that I've seriously considered buying a Scangauge. For whatever reason, I'm not picking up on clues from the car about what's happening, with all my previous cars it was easy to hear the engine and feel what was going on because of the transmission.

With the Prius, I find locating those clues rather harder (especially with the radio and AC going.) I haven't gone to the extreme of turning the radio off and won't be turning the AC off this summer (average daytime temps in the high 80's to mid 90's.)

The other thing to keep in mind is that with your averages in the 40's you're still doing a whole heck of a lot better than most cars are.

 

DWDean, try taking off your shoe. It sounds dumb but on long trips it's more comfortable and you can better feel what the car is doing and control throttle position better.

 

No, actually it doesn't sound stupid. I've noticed that my FE really does have some dependancy on the shoes that I'm wearing, or actually more specifically on the character of the soles. I'd never thought about driving barefoot, but had thought about trying a pair of thin house slippers...

 

We could really trip people out by slipping on some Simpson racing shoes before taking off in our Prius'. Hahaha



I have all the racing gear except for the shoes as they are not required till you get REALLY fast. So I guess I'll use my old kung-fu shoes, they have very thin soles.

 

So I shouldn't wear my steel toe work boots when driving?

 

Stop running the A/C and see if your MPG improves. I'm just a noob but I have watched a good 55-60 MPG average tank of gas drop due to idling with the A/C on at lights, banks, drive-throughs, etc. If the A/C is running on battery, you will have to recharge the battery eventually by (most likely) the ICE.

Another thing I have noticed is that my wife doesn't get good MPG when she is distracted. Turn off the radio and focus on your techniques. Get a friend to watch the MFD for you as you drive to give you feedback when you are doing good, and when your not. It becomes like a video game, as my wife describes it. Through the help of the advice in this forum I have coached her to getting 60-70MPG.

This is funny. Our daughter was looking out of her window the other night and saw headlights moving very slowly and she knew it was us coming. Why? Because we completely coast the whole 1/2 mile down our street, going only about 5 mph toward the last 150 feet.

 

I take it you never lived in Central Florida then. You cannot get anything from anywhere without driving. No work, no groceries, no anything.

 

Some while back in this thread dwdean wrote:

...The other thing you can do is look at your routes. For instance, my
parents will drive down the steep part of Marin in the Prius, but they
always go back up the hill on streets with more gentle grades...

I took me a while to remember that to go up hills, even at a steady rate of
speed, necessitates accelerating the vehicle. Accelerating smartly to target
speed -- 16 - 20K RPMs on ScanGauge -- then backing off the go-pedal is
said to be best for FE. In my experience, given a choice, going up the steep
side of a hill, and then no-arrow gliding the long shallow side is preferable.

For me at least, this approach was non-intuitive. The only way I could even
do test runs was to not look at the iMPG readout on the MFD on the up hill
pull. But by resetting the trip MPG reading on the SG I was able to prove it
to myself.

A practical consequence of this finding is that now my outbound and
homebound routes are usually different.

 

Shoot if I go by that criteria, I'm a failure I drive at least 500 miles/week so I prefer to frame it as "in the 5000 miles I've driven so far, I've *saved* 160 gallons of fuel."

 

I'm not arguing with the emperical result, but I do admit that I'm having some difficulty getting my mind wrapped around this. The only way I can make sense out of this is by assuming your steep hill is the most direct route to your destination. Therefore, by inducing the most efficient fuel burn you can for the shortest distance, you're getting better FE overall. Even if your iMPG doesn't look so good, there's likely some other part of trips that "makes up" for that.

 

dwdean,

I suspect that our mindsets from driving in differing topographies are getting
in the way of clear communication. In fact, I think we are of like mind,
though our perspectives may be different.

Where I am, in the Baltimore metro area, you can't go anywhere without
going up and down hills. They aren't monstrously big or long, but how you
handle them can be a big plus or minus on the daily FE.

In dealing with hills, I've come to realize that the most direct route may not
be the most efficient, either in terms of MPG or fuel used. I have found that
by taking short judicious departures from the direct route to use "hills of
opportunity," I can reduce ICE-on time and thus fuel use. Hills of opportunity
are not symmetrical; they have, in the direction you want to go, a steep up
side, and a long gradual down slope permitting no-arrow, true glide.

Ideally, as you've pointed out, you go up at your most efficient speed. It is
the immediately following no arrow glide that meets your, "there's likely
some other part of trips that "makes up" for that." Sometimes the long
down slope comes first, then the steep up hill -- perhaps a "valley of
opportunity?"

In my experience, what you don't want, if it can be avoided, is a long
gradual climb, and a short, sharp descent -- in either order -- which in this
urban setting often has a stop sign, traffic light, speed bump, or necessary
turn at the bottom.

Coming back on the same route will not, can not, net the same positive
results. If you're lucky, you can find a different route that "turns the
hills around," and doesn't add mileage.