LOW MPG's on new Prius C????

If you have less than 5,000 miles on the car, things are still breaking in.

Secondly, the car will warm up to operating temperature using gasoline so short trips will hurt mileage.

I don't trust the car MPG computer. I always divide my miles by the gallons filled at the pump for the most accurate MPG. My car MPG computer is always off by 2-3MPG.

 

1) If it was me, I would totally discount the gas from the dealer, you have no idea how full it was, how much idling they did, etc. Do not stress about that tank at all.

2) Learning the oddities of you new car is way more important than gas mileage, finding your blind spots, where the emergency flashers are, how to operate the stalks and buttons, etc. can save your life, 55 MPG can save a buck.

3) If this is the third or forth tank and you are comfortable, time to begin learning to get the better mileages. When first started, the computers want to warm up quickly to get the lowest emissions possible, in this mode, gas mileage is not one of their concerns, and you will not get spectacular mileage. Once the car has warmed up (and you might as well drive it until it does, you are getting 0 MPG just setting there) then the car is in the mood to get great mileage! My graphs in my Gen 2 always look like this (level ground)


The limit varies due to temperature (warmer is better until 85), wind (tailwinds or still air is best, side winds the worst), and weather (wet roads cost 5 MPG) so that it may take from 5 to 20 minutes to reach my limit on that day. But every day my graph looks like this. Since I drive 120 to 250 miles a day I get a lot of ideal gas mileage with just a short curve at the front, folk with short commutes may always be on the curve.

4) Once you learn how your current driving style yields MPGs, this site offers advice on how to modify your style. So far as I know, rural mail carriers have the lowest MPGs (mid 30s) as they do little but accelerate and then brake at the very next mailbox, not a driving style one would choose for MPGs.

5) Isn't it great to own a car where 40 MPG is something to complain about? Here is a link you can use to give us more information about your style: http://priuschat.com/forums/gen-iii...-answer-these-questions-esp-if-youre-new.html

 

Nobody gets 50mpg right after a cold start. It takes me about 15-20 minutes to get up to that mpg but the car will happily stay above 50mpg at that point unless you really mash on the pedal. The short nature of the trips is your problem. In a gas only car you'd also be well below EPA on those trips.

 

I drug this back over here, hope you don't mind.

Since the car is new, I wish to tell you about tire pressures.
Toyota chose the specified tire pressures to achieve the greatest comfort, and I think they succeeded at that. 35 lbs front/33 lbs rear (Never exceed the Maximum on the tire itself, no matter what I say)

However best handling and longest wear are likely higher than this, in my Gen 2 42/40 seems best. (this will vary by tire so all I have are examples)

Best gas mileage should be even higher, but I put safety before mileage or comfort.

So inflate your tires to near the maximum on the sidewall, (I would leave the rears 2 lbs lower than the fronts) and then lower the pressures until you get the ride you like.

Now watch for tread wear and adjust for 'odd' wear.

 

"- What fuel economy are you expecting and why?
- I am expecting roughly 53MPG as claimed by Toyota."

The mpg numbers listed on the sticker come from lab tests, using strict EPA protocols which are supposed to simulate driving. They are NOT numbers you are guaranteed by Toyota to get. Because mpg's vary all over the place depending on a lot of factors. To give you an idea of the variability, I "get" 40-45mpg commuting from Medford to Cambridge in cool spring weather. I "get" 70-72mpg driving from my home in CT to Medford on a warm summer day. If I drove that same route faster, I could "get" any mpg I wanted to from 72 all the way down to probably 40mpg, depending how fast I drove. Same car, same driver, same route.


"- How long are your trips?
5-10 miles"

Short trips are really really tough on mpg for any car. The engine barely gets warmed up by the time you arrive, so you have almost no time to "average out" the poor fuel economy you got while the engine was warming up. The fact that the Accord you had previously was giving you 15mpg, well below its EPA of 21mpg, suggests that your short-trip usage will make getting good mpg tough. Not to mention all the un-sync-ed lights, Boston traffic, and rough pavement.

If health and weather permit, bicycling around Boston is much faster than driving, and no parking issues. Until I hurt my knee, I left the car parked and got around Medford/Cambridge/Brookline/etc by bicycle.

 

Actually - I start out under 10 MPG - sometimes way under. Get to about mid-40s or better on the freeway.

Check your overall average and see if you are getting around 49 or 50 MPG. I run A/C all the time, make little effort to drive for better MPG and my average hovers between 49 and 50+.

Edited to add: Okay - Fuelly makes a liar out of me. C says 50 but Fuelly says 46.9. I'm happy though as I still drive with my A/C on except on cold mornings. Which is like 70 here in Honolulu.

Actually - I'm assuming the dealer gave me a full, topped-off tank. We'll see on the next fill-up - which may be a couple weeks from now. I also filled up with about 15 miles left on my cruising range - if that makes a difference.

YMMV (literally!)

Edited to add2: I've never used the "Eco" or "EV" buttons. Maybe my MPG will go up if I try the "Eco" setting??

 

Yep. OP should read Car and Driver: The Truth About EPA City / Highway MPG Estimates | PriusChat to understand the EPA tests.

The only cycles in which they start off w/a cold engine are the city tests and they are 31.2 minutes long w/11 simulated miles. They also don't drive on a real road (they use a dyno) nor do they measure actual fuel consumption, but derive it based on tailpipe emissions.

Also, we really should be measuring "gallonage". See http://priuschat.com/forums/other-cars/95536-car-driver-mileage-no-its-your-gallonage-really-counts.html.

Here's the calculation for you for gas used over 100 miles. The shortfall of what you got on your Accord is far greater in terms of gallonage than your shortfall vs. Prius c EPA city rating

Gallons used over 100 miles:
21 mpg -> 4.76 gallons
15 mpg -> 6.67 gallons ---- difference: 1.90 gallons

53 mpg -> 1.89 gallons
40 mpg -> 2.5 gallons ---- difference 0.61 gallons

For the gallonage difference to be about equal, the Prius c would have to achieve ~26.5 mpg.

 

May I ask what car you drove previously and what type of MPG were you getting from it? It could be your 5-10 mile cycle is just difficult to achieve good MPG numbers.

 

From post 5

 

Also the EPA uses 100% gasoline, no ethanol, when
conducting the EPA MPG test

 

Be gentle with braking, not acceleration. Pump up your tires. If you are dealing with a cold engine, they make engine block heaters, but it is just one more thing to plug in/unplug each day.

PriusChat Shop : Toyota Prius Engine Block Heater [Prius EBH] - $59.00

 

Yes- there are two things (at least).

The first surrounds the mechanics of how you're driving. Make sure that, from stops, you're using the ICE (gas engine) to accelerate (conservatively) up to a cruising speed, THEN let off the gas to engage the EV, and use the EV (as little as possible- a sliver of it, if you can) to maintain the speed. This will make your mpg skyrocket. It's like gliding, except that you have a little bit of electric power being used to maintain your speed. Don't use the EV to accelerate- you'll drain the hell out of your battery. And don't use the ICE to maintain speed at low speeds- that wastes energy maintaining engine speed.

ICE = acceleration
EV = maintaining speed at lower speeds

Secondly, think ahead about where you're going as much as possible. Try to time your speeds in such a way that you lose as little momentum as possible. Just as one example, this may mean, when approaching a red light, slowing wayyy down, wayy before hitting the light, so, that by the time it turns green again, you haven't yet hit the mess of cars in front of you and are still doing 10-15 mph. There are other tricks as well, but maintain as much of your momentum as you can. And use the EV to maintain speed, not the engine (again, a sliver of EV, where possible).

 

Check the links in my signature, as well as (if not among those) find the warming up stages thread for the gen2 or the gen3. Not fleshed out yet for the c that I know of, but likely closer to the gen3. Just understanding will help. Also, if you can plod along for the first minute or more on a cold start, rather than having to accelerate onto a freeway, you'll have less of a hit.

Learn to pulse & glide in sync with traffic flow, once the engine is warm. Let the engine be off a good portion of the warm time in city traffic.

Note that 15 is to 21 as 38 is to 53, so at 40 mpg, you are doing a better % of EPA with the c than the Honda. Not to mention Cwerdna's gallonage perspective.

We have a lifetime average of 50.2 mpg in spite of a 1.5 mile commute. That's not to say we get 50 mpg on the 1.5 mile commute though. Maybe close on a hot summer day with no AC, but we have had a few tanks dominated by the 1.5 mile drives that struggle to hit 40 mpg. But once warm, I can get in low 60's on the freeway and mid 70's on longer city drives. This with the larger liftback, though it takes study and practice and willingness to change driving habits.

 

The prius c will deliver the mileage advertised...but not every second. As you know and many have stated, short trips are not the best for high mileage...but one way to look at it is that these same trips are not good for anyone. You are still beating all those other vehicles driving next to you given the same route.

These cars seem to start to register higher mileage around 8 miles for me. much shorter then that and not too great a showing. Remember, this mileage stuff is all about averages...I have trips that post 56 mpg, and some around 40. Totally dependent on the driving situation.

I just looked at my summary screens and I now have 1046 miles on my "B" display, average 44 miles an hour with 49.3 miles per gallon...to me, thats fantastic...its twice as good as my rav 4, and 3 times as good as my tundra.

Enjoy your new car!

 

I agree completely.

A ScanGauge2 (ScanGauge - Trip Computer + Digitial Gauges + ScanTools I think) can help you tell if the ICE is on or off. Set one of the gauges to read rpm and if rpm=0, the ICE is off. A ScanGauge is overkill for just this, but it can also show you a lot of other things that you can't see in the Prius displays.

 

I am a little surprised you are only getting 40mpg, even considering that your trips are very short. I have used 3 full tanks of fuel in my Prius C, and am averaging 52 miles per US gallon, in spite of the fact that temperatures were subfreezing in the morning here in Canada until a couple of weeks ago. The trip computer MPG figures agree well with my calculations from distances travelled and the amount of fuel added. My mileage is virtually 100% city, and the longest trip I routinely take is only 6 miles, which is the commute distance to my workplace. I find my Prius C actually warms up very quickly compared to any other car I have driven, because it has an exhaust gas recovery heat exchanger which uses heat from the exhaust to heat the coolant until the engine warms up. I think the standard Prius has had this feature since at least the 3rd Gen. We had snow here one day in April, and the rapid warm up also helped by rapidly defrosting the front window.
Short trips from a cold start definitely hurt fuel economy, but I expect the degradation would be even greater in a vehicle without the exhaust heat recovery system.

 

It takes time for the Prius to Warmup
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When the temperature is about 60 Fahrenheit degrees (morning), my 2010 Prius III starts at about 11mpg when it starts off from a cold start on the first minute then by the second minute the Prius is at 18mpg and by third minute its climbed up to about 24 mpg and by the 5 minutes the Prius is doing about 34 mpg by the 10 minute I've edged up to about 44 mpg most of the time. Depending on the outside temperature, it takes me atleast 20-30 minutes to get to 50 mpg. If I could pre-warm up the Prius gas engine to 90F with an engine block heater I probably could get to 50mpg sooner...

Speed kills
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I can sometime achieve a round trip 70mpg average (like today) on my 15 mile/50 minute one way (30 miles/140 minute round trip)commute route which is designed to take advantage of certain Hypermiling techniques. On my regular commute the top speed is about 50 mph(for only a few seconds to climb uphill) and my average top speed is about 35 mph - but when all the stops are included my average speed is closer to 17 mph. However, when I go on special trips over the superhighway my mpg drop to between 53mpg to 60mpg because I am going at over 55 mph most of the time. If I keep my speed between 50mph to 60mph on the super highway - I can get about 54 mpg to 62 mpg most of the time. However, as the Prius starts going faster than 55 mph its fuel efficiency starts to drop... At 80mph on the superhighway using cruise control - my Prius fuel efficiency drops to about 44 mpg.


oooh I remember the day...
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Over two years ago, I got about 56 mpg on my first fillup (7.7 gallons, 436miles) on my 2010 Toyota Prius III . I was trying really hard to hypermile ...but with the tire pressure set to 35 psi front and 33 psi rear AND with the Prius set in Eco mode while trying to climb uphill from dead stops - I was surprised at how the Prius burned gas like crazy unless it was accelerating really slowly ... now I know better..

hilly roads = Power or Normal Mode
flat roads = Normal or Eco mode


Mine and your mileage may vary
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I've got my lower grill blocked (for the ICE radiator) but my upper grill unblocked (for the Traction battery inverter radiator). I've got my Yokohama Avid s33D tires overinflated to 50 psi front 48 psi rear (max rating is 44psi). I am using a ScangaugeII to help me with certain hypermiling techniques. Going to work during the first 30 minutes that I'm driving its slow-n-go suburb driving and the last 30 minutes is stop-n-go urban driving. I drive about 15 miles in one direction. Going to work, I go downhill from an elevation of 500 feet to an elevation of 300 feet. Going home, I go uphill from the elevation of 300 feet to an elevation of 500 feet. With warm temperatures, dry roads, light traffic, and a bit of luck I can sometimes get +70 mpg.. but most of the time I'm just doing about +60 mpg. My entire mileage log is at cleanmpg.com under "HyperDrive 1"

Learning to drive the Prius was an uphill battle for me...
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I accelerate much faster now because I know a bit more about what to do... on hilly roads it is often better to set the Prius on Power or Normal Mode because its gives the Prius faster throttle response time for timing accelerations before going uphill. It is always better to pick up speed before climbing uphill on a Prius. The Eco Mode which dampens the throttle makes it more difficult to time the Prius accelerations before going uphill. Accelerations going downhill, on a flat surface, or in the transitionary upswing curve going from a downhill to an uphill is going to be more energy efficient than accelerating on a uphill grade. Timing the Prius' acceleration is very important in maximizing the Prius' fuel efficiency. Hypermilers call this technique Driving with Load (DWL).

Stuck in Traffic jams
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If you are stuck in a traffic jam for longer than 10 minutes, you must avoid draining the traction battery lower than 50% (4 bars) when your traction battery drops below 55% (5 bars) and you are stuck in a <10 mph traffic jam and you know you'll be stuck in traffic for longer for more than 5 minutes more then you need to focus on using the gas engine instead of the electric motors for crawling around in bumper to bumper traffic until you are out of the traffic jam's gridlock. You do this by pressing the accelerator hard enough to active the gas engine and then letting go of the accelerator once the Prius gets to about 10mph to 15mph and then letting the Prius glide/coast the rest of the way before stopping. If you done this correctly - the Prius will be gliding at about 5mph to 10mph before you need to make a complete stop using the hydraulic brakes ( this can be tricky). What you want to avoid is draining your HV battery lower than 45% soc (3 bars) - if that happens then Prius will automatically activate the gasoline engine and run it for about 5 minutes to push to push the HV battery state of charge to 50% (4 bars) to protect the battery, but this can cause the Prius' mpg to drop by about 5 mpg - I have a extra tool called a ScangaugeII programmed for the xgauge SoC which monitors the HV battery state of charge so when I get stuck in traffic (and it happens 2x a day with me) I work extra hard to avoid having the SoC drop below 50%.

hope this helps
Walter Lee
aka "HyperDrive 1" at Cleanmpg.com
2010 Toyota Prius III blue ribbon/dark grey oem floormats
Yokohama Avid S33d (50/48)
ScangaugeII*2
grill blocking (top=0%,bottom=100%)
odeo=+23000 miles/ overall +59mpg

 

They're semi-useful in comparing ratings between vehicles but per Your Mileage Will Still Vary

Besides the suggestions already given, you could consider grille blocking but I wouldn't advise at all in warmer weather like now. You could also consider an engine block heater to reduce the warmup time. This should help a lot in winter.