So I recently purchased a used s500 with a clean carfax, and had my mechanic take a look at the vehicle. The car was riding great for about a month until a few issues came up. The first issue was at about 40mph, there is a "whirring" noise. Transmission is fine, so my buddy told me it might be the carrier bearing (probably not wheel bearing because the noise is not any louder when you turn a certain direction.) It does not affect the ride at all, just wondering if this is an issue I should get fixed immediately because it might cause further damage down the line.

Secondly, the tire sensor light has come on. After adjusting the tire pressures, the light went away. After a week or so, the light has come back on, and the dashboard computer has directed me to take the vehicle to a workshop.

Thirdly, and this might be related to the second issue, the MPG sensor seems to be off in my car. I live in the suburbs so its pretty smooth driving, and the car showed a 19mpg for the first few weeks. After a while, I noticed the MPG declining even though my style of driving did not change. I noticed there was a definite problem one day when I turned on the vehicle, and the MPG sensor was at 15mpg, then while "warming up" the car for 2 minutes, it dropped to 14.5 without having the car move an inch. My buddy told me that the tire sensor could be messing up the mpg sensor, but I'm a bit paranoid and am afraid the car is leaking fuel somewhere.

Anyone with any and all inputs would be really greatly appreciated. I love the car, but these seemingly minor issues are driving me crazy! In addition, If i could narrow down the problem, maybe it wouldn't cost me an arm and a leg to repair this. Thanks guys!