Dropping MPGs on 2010 III

Yes, I have some thoughts. By the way, my III is one month newer than yours, so I'll be curious what you find in case the same happens to me.

1. Reset trip B, turn off the AC, roll down driver and rear passenger windows a little, go for a typical drive and see what the mpg does. Granted, it may need to be early morning or at night. I would definitely find out if AC is the cause. If mpg ok on this test, then run the same test with your usual AC setting for comparison.

or 2. What setting do you have the AC on? Set the temp higher than normal, as high as you can take, and see if mpg improves.

or 3. What changed coincident with the drop? Was that when it got so hot?

4. Do you know anyone with a scangauge? This can be very useful in watching various temps, rpms, etc.

5. Have you had the oil changed? Often dealers and others overfill which can hurt mpgs. Check the oil. It should not be over the full mark.

6. How many miles on the clock?

7. Check and report tire pressure. Should be minimum of the pressures on the door placard; better more toward maximum sidewall rating, say 44 front/42 rear. The tpms is not very sensitive, so you could be very low without getting a warning light.

That's all I can think of right now.

 

Not to hijack this thread but a question....

So how does the AC affect mpg? Is the the lower the temp or the higher the fan speed?

 

Please answer most of the questions at http://priuschat.com/forums/gen-iii...-answer-these-questions-esp-if-youre-new.html. That would give us a lot more to go on.

 

Heat exchange is the bigger drain versus fan speed, but both use power from the gas tank.

 

I would think the tire pressure has a lot to do with it. Check that and see the difference especially with the weather getting so hot the tires tend to grip the road more when the pressure is low.

 

Laura, something is wrong. Once found, the car should at least do what it did at first. Should do better as you learn to exploit its potential and as it breaks in.

Tire pressure, a dirty MAF sensor, a fouled spark plug. I don't know what, but I would bet an experienced mechanic can find it, no hybrid experience is needed (my guess).

 

Could you describe your typical commute/drive in detail (distance, speed, and elevation change if you have that)? Short trips are a FE killer.
Totally understand wanting to get at least close to the EPA ratings!

 

what you are experiencing shouldn't be normal. i run the a/c full blast on auto all the time, and i still avg 50 mpg. It could be our tires. It could be a clogged air filter, hell it could be a faulty battery.

It could also be your brand of gasoline. What are you filling? have you tried something different?

 

Is that continous or do you make many stops (park, turn off car)? Seems like what you have describe, you should be getting in the 60+ range like Mark57. I am thinking something is wrong with the car too.

 

Laura, regardless of where you are or how you drive expect to get ~25mpg over the 1st 5 minutes because the ICE runs just to get warm. Operating temp is ~190F. The 2nd 5 minutes of continuous driving can start delivering 50mpg.

Turning the car off also drops the FE as the heating process restarts. When outside temps are moderate I leave the car on & locked (manually) for quick trips of 5-10 minutes. If the OAT is in the 90's F leaving the car sit will drop the battery's SOC.

Can you up the temp on the AC? 73 sounds cold. My car sits outside all day with the windows up & we've had more than our share of 90+ days. I keep the AC at 78-79 with the fan speed at 1-3 bars.

I really suspect your tp. IMO the pressure on the door is very low. Read the tire's sidewall. At that pressure you'll get longer tire life & better handling.

Since the oil is within the 2 marks on the dipstick it isn't overfilled so that shouldn't be a cause.

Do you coast up to red lights or race up to brake to a stop? Accelerating & braking at lights isn't efficient. Can you reduce your speed to minimize the braking?

I dare say that for many of us if we kept the car at the stock configuration we wouldn't be getting the FE we do.