Disappointing mpg

<div class='quotetop'>QUOTE(Rick692 @ Nov 13 2007, 01:53 PM) [snapback]538953[/snapback]</div>

You got it. And it uses neither when they're not needed for propulsion. That's why, unlike other cars, the Prius' EPA rating is higher for city driving than highway. 50 MPG is respectable for the highway at those speeds. Now, hang with us awhile and search and study up on high fuel economy techniques for city driving (like "pulse and glide"), and you might see those city numbers go up substantially.

 

Rick692 Dont be disappointed. I have never gotten 49 or 50 MPG on a tank of gas yet. Over 6000 miles so far. My normal avg. is about 45. If you get 50 doing 70 , thats great.

 

You may have mentioned it but what did you get with your previous vehicle on the commute?
Just to keep things in perspective, I have a choice of driving about 10 minutes rural, 10 interstate, and about 5 city. I can also take several different routes which, while they take longer, I can go at a more leisurely pace.

When I first had the car I immediately hopped on the interstate route and drove like I always did--jack-rabbit starts, last-minute stops, 5-10mph over the speed limit whenever possible. I got around 45-45 MPG. Quite an improvement over the 12-16 in a truck.

I have changed my driving, to include anticipating traffic, avoiding traffic when possible, using the cruise ALOT. A.L.O.T.! Especially on the rural drives and highways where it's easy to race or go deep into the pedal or whatever--subconsciously. I anticipate lights, and feel the car, watching the grades and so forth.

I'm working on my first 53MPG tank right now, and that includes the warm-up cycle every morning and every time the engine cools off for a couple hours. I look forward to driving in town where I can increase my numbers, too, and frankly, don't much mind if I add another 5 minutes to my commute. It's a game and I'm enjoying it alot more than stressing out on the arselecke factor.

Incidentally, I drove up to Auburn the weekend before last averaging roughly 76MPG and my mileage was around 46. Someone here said, "55 @ 55" was a good rule of thumb.

Hope this helps.

 

70+ MPH is not going to get great MPG.

If you are not strapped for time, bring it down to 55 MPH and watch the numbers increase.

I drive 120 miles a day and the difference between taking the Interstate and a state highway parallel to the interstate the MPG increase is satisfying. At 75MPG Interstate, I can get maybe 49 mpg. If I use the state hightway going 60 MPH with only 3 points where I must drop to 45 MPH for 1-2 miles, I can get easily 54 MPG. I'll take a 10% increase in MPG. I do lose "TIME" since I go slower, but that just gives me more time to decompress.

Why did I not go 55? 60 MPH is the speed limit and everyone wants to go 70mph like on the interstate. Just too dangerous to go that slow and have impatient people cut me off all the time.

Now that I have 30,000 miles on my Prius, I find that it does better on gas mileage. Some people say there is no break in period for the car. Maybe it is the break in period of the driver and the driver learns to drive the care more efficiently. Could be both.

Hope that helps.

Oh, I just run cheap 87 octane.

 

As a very new member, I am just learning how to use this forum. As for mpg, I am very disappointed with how my Prius fleet, (I have two of them, a 2004 and a 2006), is performing. The 04 is averaging 41.78 mpg over it 80,000 miles of service, and the 06 is averaging only 40.04 over its 10,000 miles of service. I had the local Toyota dealership check out the 06 prius, but nothing was found.

Both Priuses have the traction control option. And I have always wondered if this option derates the performance. Comments are welcome here. I do live in the northern climit, Green Bay WI, so winter time milage is lower, usually mid 30's. Summer milage is mid 40's. This is not the milage I had expected.

I have tried different driving habits; fast starts, slow starts, punch and glide. Anticipating stops works the best for improve mpg. Both of these cars travel 70% on interstates @ 73 mph. I see a major mpg loss over 60 mph.

I do not believe driving habits will provide the milage I anticipated. I believe it is more to do with how the computer operated the fuel system. These things I can not change with out the knowledge and tools.
What is the experience of subscribers with mechanically improving mpg?

Thanks

 

<div class='quotetop'>QUOTE(TonyPSchaefer @ Nov 13 2007, 10:06 AM) [snapback]538965[/snapback]</div>

Come on Tony, you know better than that. The ability to shut off the engine is a fairly small part of the Prius's incredible mpg numbers.

The reason the Prius gets worse fuel economy on the highway is because of exponentially-increased wind resistance at highway speed. The anomaly is not that the Prius does better in town: The anomaly is that conventional cars do so much worse in town. And the reason is the abysmal inefficiency of internal-combustion engines at low power output.

The Prius gets its efficiency by more closely matching the power plant to the application, which it can do because the electric motor provides torque when needed, and by using the Atkinson cycle, which is more efficient but produces less torque, which, in turn, can be made up for with the electric motor as above. Also, the use of two electric motors and the PSD, in place of a transmission, reduces transmission losses.

The ability to shut off the engine is relevant only because it allows the engine output to more closely match its optimum, with extra energy being stored temporarily in the battery, and retrieved when needed.

 

Air resistance is your enemy at high speeds. In ANY car, air resistance increases EXPONENTIALLY as you increase your speed.

 

Your aftermarket alarm system sounds like a piece of cr@p and not worth the trouble. Tell the dealer to disconnect it. If it were installed incorrectly it could drain the 12V battery and leave you stranded. (And you can be sure that you did pay for the damn thing, one way or another. Name the dealer, please, so that others can avoid it.)

Set the cruise control for 67 MPH on a long trip and you will get noticeably better fuel economy.

 

It took me a while, but I am averaging 53.5 MPG now. I definitely got a boost after 5000 miles. Granted, I live in L.A. where the climate is very friendly about cold mornings and drastic cold temps. But, when i first got the car I was averaging 42 MPG, and once it went as low as 36.

Through the techniques I learned here on PriusCHat, I have modified my driving styles to achieve what I consider a very respectable mileage given my trip to work is only 7 miles each way. I tried many different routes and found one that works the best because of slope and traffic patterns. (And it truns out it is the quickest one too- an added bonus.)

I don't have any mods at all- and the car stays outside all night.

The best thing is definitely P+G and the more you do it the better you become at getting away with it in traffic without annoying other cars around you. Alot of it is predicting what's going to happen up ahead. If you know the stoplight two lights ahead will turn red, then go ahead and use EV (very light accelerator pedal.) Most of the time cars behind will tolerate you because they can see that it will be red anyway.

If you see the light is definitely going to stay green, then give full accelerator and get the gas running and then let up once you clear the intersection, then glide.

Once I get off main drags into neighborhood streets, if there is no one arond me I use EV, even if it means I can only go 15 MPH.

So, all this to say that driving technique does matter.

 

there's only one trick for recapturing mpg on the freeway.....SLOW DOWN. There is no other way, once you slow down (say 55-62mph) you will see the mpg you were hoping for.

 

I forgot to add in my previous post that on the highway you can usually find a truck that has a governer on it, going 60 or so. Just get behind it, at a safe distance of course, and hang. That way the agressive drivers will not hassle you because they will notice the truck and figure you are just caught behind it.

I've also used this technique on city streets, but it's harder to come by, obviously. If I see a delivery truck, or a bus even, I'll stay behind it which enables me to P+G more easily.

Sure, some may say why waste the time, but it's worth it to me when I see the 53.5 MPG. My goal is to get to 55. I doubt I'll ever see 60 because my trips are too short.

 

Driving my car home from Melbourne (Australia) I got 4.5 L/100km (52 US mpg/62 Imperial mpg) while I was travelling in the 100km zone (62 mph). South Australia's speed limit is 110 (68 mph) and I averaged 5.0L/100km (47 US mpg/56 Imperial mpg) - this section was hillier, so it's not a completely fair comparison, but it was obvious the extra speed made a huge difference in fuel consumption.

Around town we're getting 4.3L/100km (55 US mpg/65 Imperial mpg), which includes some 80kph sections (50 mph) and quite a few hills.

I think your highway economy looks pretty good. I personally find I get much better economy without the cruise control on, I find it is fairly aggressive with the throttle by comparison. It might be worth experimenting with, but a lot depends on the weight of you right foot!