New owner, disappointed in mpg...

....bigger legislative implications here, repubs raising speed limits going up in my state at least to 70 maybe some 75s. In all candor many drivers add at least +9 to that. This is may be wiping out any proposed CAFE increases. EPA needs an 80 MPH highway test if we expect to see any true gains of CAFE increases. That's stupid but I do not see US slowing down soon.

PS- My 06 can hit those speeds effortlessly, not saying anything wrong with the car

 

CAFE only uses the old low speed (~ 48 mph) test cycles in the MPG calculation.

 

sounds normal... remember.. it's a speed LIMIT.. you don't have to pass it. you'll get better mileage at about 72 and below. the numbers are odd.. from what i've seen there's sweat spotts.. like 55, 63, and 72.. all depends on how your speedometer is calibrated.

when originally designing the prius, toyota said there were 7 emulated gears.. (that pretty much tops out around 70 i feel)... anything more and your losses go up too much to get decent milage.

i learned through working (pulling a trailer) that i get rather wonderful mileage if i never break 65... speed limit with a trailer in California is 55mph. while towing my trailer i didn't get below 45mpg. without a trailer it's in the high 30's or low 40's at the time because i liked to drive faster. (i'm also not on stock wheels)

on recent longer distance runs with my trailer i've seen as high as about 48mpg... for the trip.

btw.. back to topic... it's too cold there to get decent mileage without either and engine block heater or grill blocking... or both...

another btw... check your 12v battery voltages. there are several topics on it, here at priuschat. i check the sitting voltage (which could be a dirty lie)... go to ign on (not ready)... let it sit for a good 30 seconds and take the voltage. then go to ready and verify 14v to confirm it's getting charged. (if it wasn't you would have had problems already.. but it's a thing we check)

if you just got the car, the previous owner could have accidentally let the battery drain once or twice. your car isn't exactly ready to have a 12v failure.. but it's simply one of those things you need to keep an eye one. i'de give your battery another year or two. if you want peace of mind change it now... but i really don't think it's your mpg problem.

 

Great post....!
Driving habits and possible low 12v suggestion are good places to look. Not to mention tire pressure and allowing 2 min warm-up.
I pay strict attention to the "always-looking-ahead-minimal-braking" driving style. Plus for the short distance I do drive highway, I always stay to the right...I baby pulse on inclines and safely draft when possible.
This style of driving not only saves on fuel/brakes and wear&tear...it's a million times better for healthier blood-pressure.

Also.... I listen to music no sports talk-radio or the doom n gloom news.
Relax and enjoy the ride!

 

An engine block heater will do very little for overall MPG for the OP's very long commute. It helps far more for short trips where the engine warmup takes most or all of the trip.

Grill blocking does sound worthwhile, because it continues helping for the entire trip. But once the weather warms, a ScanGauge will be needed to monitor engine temperature.

 

a lot of people found that if temps get near 60f outside then grill blocking comes off completely. otherwise it's reduced grill blocking unless it's colder (don't recall the number, i'll assume closer to freezing). there are many post on here about it. be sure to post back here with results. (most important part of these forums)

 

Yep. It would really help us if the OP answered the questions but I don't think one can eek out that much more mileage on a Gen 2 given all 3 conditions below.

Yep.

The OP would be well served by reading http://priuschat.com/forums/other-c...uth-about-epa-city-highway-mpg-estimates.html. One should note that the highest average speed on ANY of the EPA cycles is 48.4 mph.

 

...wow, Prius c getting good MPG at 73 MPH...see Danny's review

 

But not at sub freezing temps with snowtires at 78 MPH.

 

I've had my 2012 liftback for a week. While I was driving it (the first 250 miles) at 55 on state highways, I was getting 48+ consistently. My husband drove 250 miles or so on interstate highways at 75+ this weekend and got 43.1. It is my second Prius (I had a 2001 bought new for 7 years), so I tend to try for high mileage. He just wants to get "there." Different drivers, different mileage. I'm hoping for 50+ overall when it gets broken in (when I drive). When he drives, all bets are off.

I guess my point is that you can control some of the variables, it just depends on your priorities.

 

^^^
Sharol46, your mileage figures aren't that useful to the OP since the OP has a 2nd gen. The 3rd gen does better on the highway and overall than the 2nd gen.

 

Did you read her last sentence?

 

I've run the I-5 interstate thru central Calif a number of times at 80 MPH and find what you describe with the charging to be ture; most of the time it is charging the batteries and not powering the car.

Did you skip over the one post about drafting? I've noticed that while drafting behind a bus, truck or even a large SUV, the MPG at 80 MPH is around 44. Moving into the empty lane and the mileage drops to 34 MPG. You don't need to be right up on the other guys bumper. You can leave 3 to 4 car lenghts between and still get good results.

 

I don’t mind driving near the speed limit (55-65 around here) as I think of my car as a car, not a time machine. If I’m running late I don’t bother making up the time. That said; if I had a 180 mile commute I’d be yearning to get there just as much as you.


More efficient tires will make a healthy difference but at your speeds you are mostly pushing air around. Head-winds and cross-winds make a large difference in aerodynamic drag so you would have to do a good number of consistent runs to precisely determine how much of a mpg difference 5mph makes. If you gather that data you can weigh your time against your fuel expenditures to optimize your happiness.


A long time ago I was curious about how much it cost me to drive faster in my 3-speed corolla. When I did the math I found that it cost me more per hour saved than I made at work. If I saved 1/10th of an hour but it cost me an extra $1 I could arrive at home with more money by working less time and driving slower. I re-ran the calculation after I got my new job and car and, at least for the speeds I travel, the situation is reversed with one complication: I work a fixed number of hours. Now instead of simple math I have to determine how much my time is worth to me. In the end I decided that it was enjoyable to try to minimize fuel consumption while staying within typical ranges (limit +10, -5). I use the torque app on my phone on every drive and those numbers give me something to look at beside the speedometer.


The Prius may not be yielding you the mileages you were hoping for, but it is still doing better than almost any other car could. Only things that can beat it on the highway are a ‘00-’06 Honda Insight or the aerocivic (65 mpg at 80 mph but it took many manhours of labor to get there).


The attached spreadsheet is a simple calculator that allows you to determine how your speed impacts your time and gasoline consumption.

 

You are observing what the rest of us observer. Slowing down from 75mph to 70mph is worth around 4-6mpg and slowing down to 65mph is good for around 50mpg is you have good LRR tires. If I drive at 60mph I see 55-57mpg. Refer to the chart below. This is for a GenIII so subtract about 5mpg from the mpg at a given speed and you'll be in the ballpark for a GenII.



Your charging question is normal as well. Cruising on the freeway the hybrid system will try to keep the HV battery at between 60-65% state of charge which looks like 6-7bars. It's normal.

Crappy tires can really kill your mpg, especially if they are designed for performance! Expect to see a 4+mpg difference between an ultra-high performance (or crappy) tire and a quality LRR tire.

 

Assuming all other mechanicals/battery are operating at spec's, all other suggestions except for slowing down and getting proper LRR tires may improve mpg's around fringes but likely with negligible results. The OP already proved that slowing down a bit improved his mpg's dramatically and LRR tires is the next step for futher improvement. Go for the big improvements first - sometimes the answer is pretty simple.

 

Use regular, 87 octane gas. Higher octane gas lowers mileage in Prius.

 

I don't know if anyone yet mentioned possible use of better MPG lube oil (for example Mobil-1 Advanced Fuel Economy). I am using the 0W-30 version right now.