To come back to the manual v automatic argument, a big advantage of the manual is to be able to put the car in the "wrong" gear in certain situations. For example, shifting up a gear earlier than the auto would under acceleration, or staying in a higher gear then normal in a corner to reduce the risk of wheelspin on acceleration out of the corner which could cause a spin. Useful when grip is limited, such as wet conditions or when using heavily worn tyres. Can't do that with an auto. Sometimes even the slight change in the cars balance caused by an ill-timed auto gearchange can cause you to lose control. And then there's fuel economy- put the car in a higher gear and you'll get better mileage- useful for full-course cautions.
And yes, I have played GTR extensively. How did you guess?
Recently I've been playing a lot of Sega Rally 2 on DC. Once a couple months back i had a look at the "records" section in the main menu and saw just how many records it keeps- top 16 times in all 11 championships, top 8 in each arcade practice circuit and top 8 in every car on every track in time attack. I'm gonna set records for all of 'em. I'm gonna be at it for a while.