The short answer is: you have a fuel leak. What you described would seem to indicate a leak or some major engine problems.
Does the car run normally?
Since you didn't mention the car wasn't running bad, I assume it's running normal which would tend to dismiss a mechanical problem, like you aren't running on all the cylinders.
Let's look at some numbers, like what is the normal gas mileage on a Pajero? 19.8 for a 2015 and 19.6 for a 2005. See Mitsusbishi Pajero Mileage. Doesn't sound like it's a common problem with this car. That is the first thing you look for.
For the Worst car mileage in 2016, it's the Toyota Tundra at:
Fuel Economy: 13 MPG city / 18 MPG highway
What is your mileage? 7.84 Miles per gallon. That puts you way below the worst car this year, so this alone makes me think it's not mechanical.
Fuel systems are under pressure, so a leak may only happen when the car is running. So, this is what I would do.
- Park the car and run it for 5 to 10 minutes over a flat, dry, clean surface, like a concrete driveway.
- Use a light and try to inspect it from underneath for leaking while it's running without actually getting under the car.
- If you don't see anything obvious, back it up and look for wet spots on the surface. Red spots are trany fluid, brown or black is usually grease/oil.
- What you want is a wet spot that dries up after a few hours, that is the gasoline. If you find some, note the general location, but either way, still call another mechanic.
This time however, these are the questions you ask:
- Have you ever successfully diagnosed a problem like this, a hard to find fuel leak? If yes, continue, no means call another.
- How many have you done?
- How long did it take?
How did you solve the problem?
If the mechanic doesn't give clear, concise answers to the last 3 questions, call another one. If he has actually done it, he will be able to explain it easily. The reason for the questions is because some mechanics, as in any field, will say anything to get work, at least that has been my experience anyway. Also, it will give you some idea as to the cost of diagnosis.
One last thing, please get it looked into right away. A leak like this anywhere near the engine will cause a fire. I know of a person that this happened to with a Volkswagen bug and the car literally went up in flames. The person got out safely, but it's not something to play around with.