I have a problem. I have a 2004 Cadillac CTS (automatic - 3.6L V6) and it is terrible retaining gas. It only has 73k miles and runs pretty smooth. But idk what to replace that could possibly be the reason it burn so much gas. I put 93 premium gas. I really don't drive too much. I actually don't drive to work because I will definitely have to full up every 2 days. I just use the car to go to the mall or grocery store which is only a 15 minute drive. I don't drive fast which makes a car burn more gas. There is no message popping up that it needs maintenance. The engine oil is at 80% and the transmission oil is 58%. Idk if it's the fuel filter/pump, or it needs a full tune up judging by the oils percentage. I'm actually suppose to do an oil change at 75k miles. Any advice is appreciated!