I have a 2012 Camry XLE 4 cyl. Due to a critical situation last week, a total of 6 people was travelling in the car and after around 40 miles, I could smell gas during driving . I stopped the car immediately and checked for leakage under the car and also popped up the hood to check for leakage. But did not see any leakage anywhere. After that I pumped around 5 gallons of gas and parked it . In the night when I started the car again, the fuel meter was only little above the reserve and definitely around 2 gallons only was present in the car. Around 3 gallons were missing. I was shocked to see this and also witnessed heavy drop in mileage after filling up the car again and driving with just myself. The Average miles per gallon display suddenly dropped to 15.1 mpg from 27.1 and slowly increased and now it stands at 25 mpg. I continuously checked for leaks since then and cannot find anything on the road or wherever I park. I took it to the nearest Toyota dealer to check the car and he checked/confirmed that there is nothing wrong with the vehicle. The maintenance light came up but the service representative said that it is common and will start blinking after 5k miles. I changed synthetic oil on Oct 2,2014 but have driven more than 5k miles. I am not sure what to do . Request your valuable inputs. Thanks.

***Update***: After the above incident, I had driven around 250+ miles and the car is consuming more gas than before. I am able to notice this huge difference .

 

Is the car still under warranty, if so Toyota is responsible for fixing it. If there is a fuel or fuel vapor leak, this is an emission issue which is even more important to fix under federal law.

The fuel computer readings are not based on actual fuel used. The computer doesn't have a fuel flow meter and doesn't measure actual fuel burned, as such it can be off.

If the fuel system lost 3 gallons in a few hours due to a leak, this would be more then an air leak from the tank (fuel vapor). But a drip or small steam of fuel onto the ground. If the car was moved to investigate, there should be some evidence of liquid fuel or a fuel stain on the ground.

Have you done an actual fuel used versus miles driving calculation? This being to fill the tank was gas as you normally do. Reset the odometer and average MPG gauge. Then driving your normal routine until the fuel level gauge is now to reserve. Then refill, if possible at the same station and compute MPG based on miles driven and fuel added to tank. Then compare to the computer.

If the car has Eco-mode, make sure during the test you keep it either on or off.

Make sure the fuel type used is the same. Meaning if sold in your area, the percentage of ethanol in the fuel is the same.

You need to determine if the fuel MPG indicator and actual MPG based on fuel used versus miles driven are the same.

 

I had a similar experience with my 2007 4 cylinder last summer.... with all sorts of strange, low mileage readings.

I took it to the Toyota dealer and the service rep. said they had been seeing some problems with that function during periods of very high humidity -- and it WAS HIGH when I had my erratic readings.

Humidity dropped and the readings became more realistic. Since the original post post was made during the winter, that (high humidity) doesn't seem to be the problem, but I suspect WEATHER conditions COULD have some role in the sensor/computer measurement of mileage, or that something was simply wrong with that mechanism. Your readings may simply be wrong. (Actually checking mileage by gas used and miles driven would help resolve that point.)

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I've had no further problems since then, in that respect -- although my mileage has dropped about 10%-15% bit over the past two years (about which I started a separate inquiry elsewhere on this forum.) I don't think these current problems are humidity related, as they're not seasonal and have been obvious for a year or two.