Your car has covered under 6k miles in 12 months. Meanwhile the rear disks - always lightly loaded - will corrode.. And then you brake lightly and the pads wipe rust particles across the disk face.

So I take it you don't brake hard every two weeks - down a hill to clear the disks of rust?

You make a fair point, although you can't know for sure that the OP hasn't done as you suggested. Unfortunately we live in the real world, and one would expect original equipment not to require expert mechanical and operational knowledge of the vehicle to be applied to everday driving.

To answer the other post re disc life - I have only limited experience, of Saabs in my case, and I can only quote as I find. My 9-5 Aero estate automatic, with 265hp and 420Nmof torque, has still half the life of the front discs remaining and a third of the life of the pads after 45,000 miles. And the rears were changed for the first time at 140,000 miles due to normal wear and tear. I can only assume GM-branded brake discs are rubbish!

Car 8 months old - 6300 in those 8 months. Not garaged, rarely washed. Driven slowly? Ask my missus - she's always gripping the dash. I luurrve that turbo.....