Since we are sharing...
I have about 12,000 miles on my '04. ( Only 1,500 by me - previously owned )
No oil added in 1500 miles (dealer overfill - still above full)
Running 18 to 21 MPG (converted to US gallons or 11.3 to 13 litres/100km)
Best mileage on a road trip @ 76 MPH
Worst mileage showing off my new car with some spirited driving.

 

For me the average highway mileage is 24-25. If I really saving gas, driving at 65-70 mph (the most economical as I found) I can get 27. This numbers were confirmed on my 4,000 miles drive cross-country recently. I was very bored and watching the mileage to get some idea about that. And the oil consumption dropped considerably after 10,000 miles on the odometer. Before my trip I used to add oil every two weeks and averaged around 0.5 quart per 1,000 miles. Now, I have not added any oil in the last 1,000 miles at all because the level is still at full. I do however, baby it this time of the year due to rainy weather.

 

Regarding brands. I have found that Chevron gives the best mileage for me. Most Chevrone fills up were 25 mpg or around that. Shell gas did not show any gas mileage improvement over the cheaper brands. I noticed Albertson gas (was it Exxon brand???) gave me a good mileage of around 25 mpg, similar to Chevron. I did notice that a couple times I used Chevron gas I got worse mileage of around 22 mph. On the average I was getting around 21-22 using most brands other than Chevron and Albertson and 24-25 using Chevron and Albertson. All the gas was 91 or 93. Did not notice any difference between 91 and 93. Never used anything below 91. Over here, in Boston area, I have noticed that Mobil gas seems to be giving me good mileage (22 city+highway) as compared to Citgo (19 city+highway). On my car I noticed that mileage depends greatly on the type of commute. If I commute 15 miles every day I get around 22-23 mpg, whereas if my commute is 3 miles each way I get 14 mpg!!! That's not surprising that cold engine uses more gas but I did not think the difference would be that big.