Multiple questions, help!

[Zman83]

2000 Grand Am Gt
3.4
103,000 Miles

My first question is, what’s the average gas mileage, or how many miles to a tank of gas does a grand am gt get with 3.4 engine? Sense the cold weather settled in ive been getting around 280-300 a tank. Is this average?

Second question. When i start my car up and let it warm up, it seems that there’s a hint of gasoline in the exhaust fumes? what could be causing this?

Third question. For the longest time now there has been a vibration and a humming coming from the front drivers side wheel area. The bearing and cv have been replaced and ive swapped tires around to no resolution. What I have noticed is that the vibration stops when i turn right, it starts around 25 mph, it does it in all gears even neutral when up to speed. Also when i was driving on snow covered roads, i decided to spin the tires and go through all the gears. To my surprise i herd and felt nothing.

And my fourth question. While my engine is cold, my car is stubborn shifting into 4th gear, but once things heat up to around 100 it shifts fine. Then just the other day, the weather started warming up and i could take off and go with out a problem. Could this be because of dirty tranny fluid and a filter? im guessing the fluid is original as i bought the car used and i am finding more and more things wrong with it.
Thank you for your help.

[xeroinfinity]

1. Thats pretty good mileage, I wouldnt complain about that. I get way less but I have a leadfoot.

2. Normal, car while warming is in rich mode to warm the car up faster.

3. Could be the bearing again. Depending on who made it and installed it. Though if your brake pads are on backwards they can make a grinding noise. The wear indicator goes on the inside of the rotor.

4. Might be your trans though cold weather reaks havok on your engine/trans. If it has over 100k miles and hasnt been changed, I'd try that first. I would NOT get it flushed with high mileage.

hope that helps