My just purchased '04 3.4L V6 (PreRunner 18.5 gal tank) just had the light go on after only 260 miles. I'm going to fill it up to see how much fuel was left. I'm hoping at least 2-2.5 gals otherwise this thing is going to be a pig on mileage. It was about 75/25 city/highway.
Maybe a tune-up will help.