Bought my 2010 hybrid civic about 3 months ago with 72k miles, and an assortment of major maintenance items done including a new battery pack at 46k. My commute is 80miles round trip, 40 of that is in a FLAT 60mph stretch of road, the other half is 65 and still relatively flat. Now with just shy of 80k the cars average since I bought is 37.1mpg. The car will not get better! I have read so many guides on how to drive it and the only way the car will show 45mpg on the instant meter is if im doing 45mph and doing the let off and lightly ease back in method.

Earlier this week I did an oil change and noted that the rear brakes were catching at one spot as if the rotors were warped, so I installed new rotors and for the next 2 days following this my average jumped from my normal 32-37mpg to 58mpg over the course of 150miles.

Now my fuel economy is back to crap again four days later. Today I drove a 120mile trip that was again on flat ground, ambient temps were mid to upper thirties, and 90 of the miles were driven at 50-55mph at which I could not get the instant fuel economy gauge over 40mpg, and the other 30miles were driven at 65mph where it dropped to 35. Total average for this trip was only 36mpg.

What is wrong with my car!?!?!?!?! If this is realistic fuel economy then I made a huge mistake buying this car...

Also I do my mpg checks by actual calculation

Shoot some suggestions my way, I would greatly appreciate it!

 

Are your rear calipers dragging? Very odd for rear rotors to warp. I think you addressed the symptom, not the cause.

My '06 would get ~48-52mpg in the situations you describe, and I would expect you could get the same.

 

After changing the rear rotors there doesn't appear to be any type of drag when spinning the wheels on the lift. (I also really hope that at 80k it doesn't need calipers) My fuel economy has sucked for the last 8k miles and I find it hard to believe that they have been dragging that long because the pads still look brand new.

Are there any other obvious things on these cars to check?

Only other noticed thing is that my engine is loud, especially when cold and under load. My friends always ask if I've checked my oil level recently but it's been noisy since it got cold out. Everything I've read though seems to say this is normal.
I also cleaned out the egr valve and egr ports right after I got it. Egr ports were choked up with soo.

 

It seems that the oil change/rotor change caused a short-lived boost to mileage. Either it's in error, or it temporarily fixed a problem.

Check ECU for pending codes.

I notice a pretty substantial mpg penalty when it cools off, and Phoenix rarely gets into the 30s as you describe. Can you compare your warmer weather mileage to cold weather?

Status of CVT fluid? Genuine Honda fluid? The consensus is that you should change it every other oil change, not in accordance with the minder. Frankly, it can't be changed often enough.

0W-20 synthetic oil?

Did you check wheel spin or rotor temp immediately after an extended drive?

Brake fluid flush?

"noisy" isn't necessarily the right description for these engines. Their top end tends to be a little clicky, but I wouldn't call it noisy. Valve clearance check?

Do you get ~50% IMA assist indicated when accelerating from a stop at about 2k rpm?

Are you getting any recalibrations?

 

I have now checked brakes 3 times and they absolutely are not the issue. I check rotor Temps on each hub after a long drive and all were cool, check park break adjustment and it is good. Nothing appears to be dragging.

When I changed the oil I used mobile one 0w-20 designed specifically for Hondas (same stuff we use in the crosstour for the last 60k) and I measured it exactly because I've had vtec Hondas in the past that were very sensitive to correct oil fill.

I have only had the car since November so warm weather readings I don't have. However with my driving conditions and habits I would think my 800 mile driving average of 37.1 is too low. I live 0.3miles from the main 25 mile stretch of 60mph speed limit zone I drive in.


Cvt fluid was done at the dealership when I bought it 8k ago and level and color are still perfect.

Assisting is normal, typically 3-5 bars accelerating, but from a stop it is know to push 4-8bars with 2k rpm.

I have had one battery recal in the last 8k miles and that's it

I'm going to check for pending codes next.
The engine noise is very close to this. Until I can get a video myself this is the best comparison I can find.
I'm afraid to take if the dealer knowing that this will be a guess and check game for them and that gets pricey quick.

 

That sounds way more "clicky" than either of my '06 HCHII. Checking valve clearance might be a good idea.

The dealer or an independant honda specialty shop might be able to diagnose more accurately as the professional "code readers" are capable of getting far more information from the ECU than a parts-shop code reader, e.g., they can read the car's estimate of remaining IMA battery capacity - no consumer code reader can do that. It might be worth the ~$100 diagnostic fee to see if they can find something.

A few more questions:
1) is auto-stop working normally?
2) do you find a decent correlation between your computed mileage and the car's reported mileage - mine is typically LOW by 2-3 mpg when compared to calculated, i.e., my calculated mileage is typically 2-3 mpg better than the gauge reports.
3) are you conducting your optimal mileage testing with the car and cabin FULLY warmed up but with all accessories off? The defrost setting can hit mileage significantly as it generally disables auto-stop, and it runs the compressor.

Get the car and cabin fully warmed up. Turn off all accessories and get gauge- reported mpg for about 10 continuous miles of 45 mph driving on straight and level pavement (5 mi one direction + 5 mi the other direction will even out any slight grade) and take that info to a dealer or specialty shop with a professional code reader. In 30°F temps, I would expect high 40's or low 50's mpg at 45mph.

 

I didn't specify it, but I would recommend you use the "B" trip meter to track short-trip mileage.

For example, get to a steady-state 45mph with cruise control (all accessories off). Reset "B" trip meter to track mileage for 5 miles, record value at 5 miles. Turn around and reset/repeat for 5 miles in the opposite direction. Average the two readings obtained at the end of each 5 mile stretch.

 

1) Hybrid vehicles that are in cold environment will run 'rich' and not begin hybrid mode until the vehicle is warmed up. (this is probably killing some of your MPG's). The only way around this is to use a block heater (in the cold months). (many of us have installed in our HCHII's). If you warm up the coolant for a couple hours prior to commute, it will be in hybrid mode with full auto-stop capability faster. If this is your cause, then you will see great improvement in the summer.

2) Tire pressure - you need at least 38PSI in all 4 tires. MPG drops off fast when pressure is low, even in one tire.

3) There is a way to get at least 5MPG more just with the gas pedal. Once you reach your speed on the highway, very lightly lift off and then restore pressure on the pedal. Sometimes the RPM's will dip but your speed should be the same. There are instructions in this forum by using a ScanGauge in order to know if you are doing it correctly. I have the technique in my mental cruise control so I haven't referred back to the instructions for a while.

4) I have noticed improvement in MPG when replacing the engine air filter.

 

Updates:

1. Tire pressures are always at 40psi and I check weekly
2. Car was bought 3months and 8k miles ago at a honda dealership where it got: cabin/engine air filter, cvt service, oil, new tires, coolant flush, and 12volt battery.
3. 2 years ago and when the car had 47k (now has 79k) honda installed a new IMA battery
4. Auto-stop is working relatively normal, however it is rare for it to make it through a whole red light without restarting on its own.
5. CVT is very jerky with the current temps, but Ive come to accept this. It acts like it completely goes to neutral when cold and slowing down and then when the accelerated is pressed it revs up 200-400rpm and then engages as if I reved my 95 civic and dumped the clutch. Fluid is good both in color and level though.
6. Car NEVER has the A/C activated when heating and most of the time heat is only set to 60.
7. Discovered before these videos that the 12v battery cables were loose enough to twist the cables off, so I unhooked them for about 15min, load tested the battery and reinstalled. (Went through the recalibration before all of these tests and videos)

*sorry for poor quality filming on these videos*


This first one is a cold overnight start (20dgerees) shows some of her noises and how the cvt behaves. You notice cruising at 30-35mph shortly after take off is lucky to start hitting 30-35mpg, somewhat expected being cold but kind of pitiful considering what I used to be able to get in my 06 1.8l 5mt civic.




This next video is after driving about 2miles and getting the temps up to about 4ish little dots. It really shows how she sounds, and this noise picks up with rpm until it hits about 2k, hard to hear inside the car through the camera.




This next video is driving at full operating temp or at least 15 minutes of 45mph or more driving.... I reset my trip mpg for this one. It shows accelerating up to 55mph, and maintaining 55. I consistently drive by letting up off the pedal and easing back in to maintain speed but try to force higher readings on the impg gauge. In the video at the end it looks like its at 50mpg but its the angle, it actually about 2 dots below it. This stretch is perfectly flat and and straight and I drove a total of 10miles on it at 55mph, at the end my trip was at 37.9. Is this just normal for winter? It seems excessive but I just don't know.





I appreciate all of your comments and suggestions!!!



I drove her to upstate NY about a month ago from central ohio for a total of 1100miles and only averaged 36.8 with just me in the car. She is about to head to Tampa florida in about a month with two people and Im nervous that this whole hybrid thing is going to be an embarrassment as my co-pilot is expecting big mpg numbers and not what her 09 focus gets...


Im not much of a dealer-goer so im appreciate you all so far from keeping me informed before I commit to going.

 

I'll check out the videos tonight.

Full operating temp is 90-92°C based on my OBD car readings. On the gauge, this is approximately 10 bars or about 40% of the gauge range. If you're fully-warmed temp is low, you are going to constantly run rich and pay a mileage penalty.

I use an ELM32 bluetooth OBD-II adapter and the paid version of Torque on Android. It allows me to monitor real-time data in a way similar to a Scangage (I can monitor the IGN and LOD values that are considered key to getting into lean-burn) as well as check and clear diagnostic codes. It's about $20 total for the adapter and Torque. There are similar options for iPhone, but I haven't seen one as effective. If you're an iPhone user, you could probably pick-up an older cheap Android phone and use it as a mini-tablet.

I can monitor A/F ratio, TPS, etc. If the ECU reports it, and it's a known part of the OBD-II standard, Torque will read it.

I suggest you get a setup like the above so we can start comparing values. Otherwise, I don't see another option besides a dealer.

For comparison, my 15 mile commute, which is 90% surface streets and 10% highway. I'm averaging about 42.8 over the last 150 miles or so. Temps are around 40-55°F. However, while cruising steady-state on 45mph streets, I frequently see instant mpg readings between 60 and 75 mpg. During warmer months, I can average in excess of 52mpg on the same commute.

I think the Tampa trip might be a good opportunity to compare warmer weather performance. I would expect you'll experience temperatures upwards of 70°F.

I have one of these:

http://www.newegg.com/Product/Produc...=-1&isNodeId=1

The China clones can be problematic, but I have had great experience with two of these - one for each HCH.

Good luck,

Steve