TCH has almost 20,000 miles on it now...Past month or so mpg has fell from 36, 37 to 23, 24....NOT tire pressure...Bringing to Toyota in am BUT REALLY UPSET... Just had oil change and no difference.. In fact trouble getting it to drive in hybrid mode.....

 

Stuck/rubbing brakes? I noticed one of my rear wheels dragging a brake pad this spring. Only noticed it because the warmer weather I had the windows open and started to hear the occasional squeal. Touched the rotors on each wheel after a short drive and 1 of the 4 was burning hot. I didn't notice all that much difference driving, but after it was fixed I'm getting the best "Tank Aves" I've ever seen. Typically in summer I see (metric; lower are better) 5.9s to 6.3s by time for fillup but since the fix this spring I'm seeing 5.5s to 5.7s (5.5 is about 43mpg).

 

I have driven across a large parking for a few times with my emergency brake on. Evidently I did not have it pressed down enough. I caught this due to the sudden slow down when I let off the gas.

A big jump in your outside temperature being a lot hotter. That would really put a load on the engine when taking off from a stop. If you run the AC temperature cold like 60 or 65 degrees, this would prevent any EV operation.

Turn the AC off when in town where you can coast down from 40 to 20 mph. If the battery is charged and you have been driving on mostly level streets it should switch to the EV mode. If not I would had to the Toyota dealer to have it checked out. The engine and all hybrid parts have a long warranty.

Try checking your tire pressures only after the tires have cooled off. They should read around 35 psi.

Be sure to let us know what you find.

 

While it's probably mechanical, here are a few considerations

This is a generic list and not necessarily related to your situation. If it was only one tank, some of these might be applicable, but not likely for two tanks.
Possible situations...

• What if driver, inadvertently reset the mileage counter amidst the trip, thus recording fewer miles per tank than actually driven?
• What if the recorded amount of gas used was mistaken. I usually rely on the onscreen display (since it's always withing 1-1.5 mpg of the manual calculations). When I refuel, occasionally I will glance at the gallons purchased and 'remember' the amount. Later on I'll either write it down and calculate it, or if I'm feeling smart, I'll calculate it in my head while driving. What if driver purchased 13.5 gallons, but 'remembered' 15.3? Or if driver was Roger Clemens, what if he "mis-remembered"?
• What if the tank before the trip wasn't completely filled (fuel shut off early) and then the tank after the trip was filled to the rim, thus recording far more fuel for the one trip than actual.
• What if there was a significant difference in the factors relating to the cars performance in this one tank (or trip)? For example, if driver, weighing 140 pounds, typically drives alone with an empty trunk. What if driver traveled with four passengers each weighing 250 pounds and the trunk was full, adding an additional 250 pounds. In this situation, the extra 1250 pounds will cause the mileage to suffer. *
• What if driver typically purchases gas without ethanol, but for this trip, got some of the 'good stuff' (10% ethanol) for this one tank?
• What if tires were under inflated?
• What if there was a head wind during the trip?
• What if trip included a few stops, whereas driver typically drives long stretches without stopping?

Not saying driver was at fault, but at least, the possibility of user error has to be considered.
Again, it's probably mechanical, but some of these factors could cause a wide swing in calculated mileage.

* Supposedly, each 100 pounds reduces mileage by 2%, so could 1250 extra pounds reduce it by 25%?

 

I too have experienced decreased MPG - for the past 6 weeks. mileage has dropped from avg 39-40 to around 33-31. I had two new tires put on before the trip. Definitely had a little more weight in the car due to luggage, etc. I have been home 1 week, and am waiting to see if MPG returns to previous average - it hasn't yet.

 

I'm having the same problem. I live in Tucson and its been 100+ for over a month so obviously using the A/C. During the cooler weather I was getting 35 to 36 mpg, now its down to 30. Just had the oil changed.....the car has 6000 mi on it. Can this just be the use of the A/C? When on flat surface I'm in EV mode at 40 or under so no change there.

 

Same here with the recent temps in the high 90 low 100's. The last two tanks have been mostly around town and dropped from 34-35 to 29-30. Hope it is just the weather.

 

It's the AC pulling more amps in the hot weather. I would add if it's very humid can also pull down your mpg. I will have proof of that the next time I fill my tank. Your AC is more efficient when the humidity is low.

 

You may feel your pressing on the throttle more than normal when the AC is on. How ever long you stop when in town, as each time the cabin can get hot again. I see your 103 forecast for the next few days will sure pull on your gas mileage.

The car AC pulls heavy on the TCH till the cabin cools off. I would think being in Tuscon, running your AC on 76-77 degrees would be about right only after the cabin has cooled down. About 2 or 3 notches of fan speed on the graph. Best to kick up the fan some for about 5 to 7 miles till it cools down.

I once rode in a friends brand new Ford car. It was hot July Texas summer. He had the fan on the highest speed with the temperature set to 65 degrees. A month later he was complaining it had no power and was a gas guzzler. I guess he overlooked the car wasn't even broke in.

 

I always figured the fan used little energy in comparison to the AC compressor. I would often run the fan alone on a high setting unless it was really hot and then I would set the AC to 78-80F (probably overridden by ECO mode anyway) with the fan still set to a high speed.

I still got 50+ mpg driving on the highway with the AC on and mid-40s mpg on the return leg in heavier traffic.