I have a 2007 prius with around 315k on the dash. I've previously had a fuel tank replaced, around 60k miles/1yr ago with no issue until recent. In the last few days, I've noticed the fuel bars dropping significantly. I first thought it could be an inaccurate reading of the gauge, I lost about 4 gallons in a 12 mile drive. The MPG/efficiency reading is normal, so the vehicles efficiency is not what I'm worried about. I filled it up and drove home, the same 12 mile drive, and lost ~2 gallons. I parked the car, and there is no visible leak, no gas on the ground, but I have smelled gasoline in the cabin, only while the heater is running. I had this happen once before, around half a year ago. I was driving on the highway and noticed it dropped 1 bar every 10mi or so, after I filled up that problem resolved itself, now it seems much worse. It doesn't seem consistent, but drives less efficiently than a dodge ram with faulty fuel injectors. I'm wondering if its a fuel line, or a common problem that others may have had.
If this is really a fuel leak and not just a very bad fuel gauge, then you should have a shop diagnose it properly, and soon. There is no good place in a car to drip 2 gallons of gasoline during a 12 mile drive. However, there are some very bad places to be dribbling that very flammable substance, and unless you want to be extra crispy, it must be dealt with. My gut feeling is that if your car was really leaking 2 gallons of gasoline on that short a trip the smell would be overwhelming if this was at low speeds, but maybe, just maybe, it wouldn't be noticed at high speeds if the leak was way in the back and the wind could blow it away from the cabin.
Cracked fuel line by the tank area perhaps, only leaks under pressure when the fuel pump is raising that fuel lines pressure. Get it on a lift and have the motor running to see where its spraying
The Australian version has a plastic fuel tank and the exhaust hit something and it back against the tank, melting hole in it. Only leaked above a certain level fuel and because it was at the rear of the vehicle, it wasn't really noticeable until a hot day. The leak developed to the stage it started to make a wet patch when parked and I was finally able to trace the fuel leak. The Australian version also has an aluminium can type fuel filter hat uses the pus on and lock type fuel fittings that require the special tool to release ...... but they are known to release all on their own and spray fuel out under pressure, but only while the engine is running ...... T1 Terry
I'm wondering if it's the fuel lines, because when parked in the garage - it has not leaked in any capacity on the cardboard I have set beneath it.