Is it normal for my '01 A4 1.8T to have a sort of 'whine' at 75/3500rpm? It's kind of loud and annoying, but as far as road noise the car is very quiet.

 

wow, so much information to process.

What size tyres do you have?
What brand are they?
Is it on one side of the car only?
Is it back or front?
Is it on every road? (some roads are made crappy)

 

Good questions. I'll have the tire brand/make for you tomorrow. I know they are very wide and cool looking though Also, there is a high pitched 'tingy' vibration that I hear on the road at highway speeds and at surface road speeds...but it's not always there. It sounds like it's coming out of the left front of the vehicle...almost like it's inside the cabin. That has me worried too

 

could be a wheel bearing, but it's hard to tell from the information you provided...try making some quick lane-changes on the freeway and see if the noise changes at all. if it does, that probably means you have a failing wheel bearing.

 

Do you have the belly pan on your car?

If the noise is coming from a wheel area it could be tire or wheel bearing. If you rotate tires and it stays in the same area, it is more likely a bearing.

 

You know, I have a feeling the problem are your tires. I used to have the exact problem with noises on the freeway. Try putting on a new set of tires because this issue is caused by uneven wear on your tire. Therefore I would suggest you get new tires and fix the alignment.

 

Thanks for the suggestions, guys. I'm going to get the wheels balanced on Saturday. I also noticed that when I make turns at slow speeds I hear a strange 'grinding' noise, this also happens when I start the car in the morning when engaging the clutch, but quickly goes away after releasing it and usually doesn't come back until the vehicle has been off for a long time. Sorry I keep posting more Q's, I just want to get everything looked at at the same time this weekend. I'm pretty sure the sound is the same when I engage the clutch in the morning, but perhaps the turning issue is a CV boot and the clutch is another issue?

 

I have the same car as you, and have never experienced this on it, but I did on my previous car. It was a 97 Infiniti I30. At first it only happened when braking, but then started to happen all the time, almost like a constant grinding. I thought it was the brakes, but my friend told me it was the bearings, but since the brakes needed to be changed anyway, I tried that. Although I think it was the bearings, the problem went away once the brakes were changed, so go figure.