2006 envoy gas gage

Your gas gauge sensor is most likley the problem on alot of new cars they measure your fuel off an average of were your float is at. like if your not moving it stays in one spot but as you move the float moves and reads the lowest amout that it is averaging and if your float keeps reading low your going to read that you have alot less gas than you really do. have you tried filling the tank all the way and see what it does? if it stays at full until you use some gas and your float starts moving your gas gauge will probley go down in that case its the fuel sensor if this dont help let me know and ill c what i can find out for you