The EPA (US - Environmental Protection Agency) lists the mileage for this car at 27 MPG City, and 37 MPG highway. That's roughly 11.47 Km/l city and 15.73 Km/l highway. Granted, these ratings are under absolutely perfect conditions so they are a fantasy when it comes to real world combined mileage. So let's call it a combined of roughly 26 MPG which is 11.05 Km/l. Still a good ~40% better than what you're seeing.
At least you can eliminate the weight of the vehicle and the power of the engine. A more powerful engine would use more fuel not less, so you need not worry about those things you can't change. This looks to be something wrong with the car. And running rich is a very good possibility, and that means the comment suggesting looking at the spark plugs is a very good idea. If they are dark and sooty looking you're probably running rich. Since you just got the car a tune-up would be a good idea. I just recently bought a 2000 Toyota Camry and the first thing was an oil change, spark plug replacement, air filter, fuel filter, and whatever repair items it needed. If yours needs no repairs you would still be served well by doing the maintenance items I listed. Should be fairly inexpensive especially if you do them yourself.