I've attached a picture of my 19 year old Uno roof after what amounted to a days work. The paint had really badly oxidised, so much so that it was completely matt. T-Cut on it's own didn't have much effect, so drastic action was required. Two going overs with Turtle Wax rubbing compound got rid of most of the oxidisation. Then I gave it two going overs with T-Cut, and this time the paint came up really nice. Both these are good for developing arm muscles!
Then I used Turtle Wax High Gloss polish. I just happend to have a some lying around, I don't know if it's even still available. I gave it one coat, then a good buffing by hand. Then I gave it a second coat and used an electric buffing machine.
Then end results look pretty good I think, especially considering it's the original paint put on in 1986!
Bloody hard work though, and now I have the rest of the car to do
Gonna take ages, but it should look nice when it's done 
Then I used Turtle Wax High Gloss polish. I just happend to have a some lying around, I don't know if it's even still available. I gave it one coat, then a good buffing by hand. Then I gave it a second coat and used an electric buffing machine.
Then end results look pretty good I think, especially considering it's the original paint put on in 1986!
Bloody hard work though, and now I have the rest of the car to do