Rules are simple.
You pick one car company, and you list what you would change assuming you had carte blanche authority.
I'll start:
Ford US.
*Drop Edge
*Drop Focus/Fiesta Sedans, replace with 3 door versions
*Add V6 diesel option to F150
*Add Wagon to Fusion Lineup
*Add manual option for V6 and AWD fusions
*Drop all Shelby ties (inc. GT500)
*Use GT500 drivetrain to create Boss 429 as top-dog Mustang
*Produce the C-Max (whatever the Focus-based Minivan is that's basically a Mazda5 with different engines)
*Add Bronco based on F150 chassis using the quad-cab setup with the small suicide doors behind the main doors. 4x4 only. Same engine choices as F150.
--Lincoln
Kill entire lineup
*Create Mark IX based on Shelby GR-1 Concept
*Create Continental as fresh sheet uber-luxe sedan on par with BMW 760
*Create Zephyr as entry-level Lincoln. ~CTS-V competitor; Fusion chassis with 4.0 version of SHO motor, DSG and 6-speed options, AWD standard.
--Mercury
Bring it back; offer dealership contracts to anyone that had one before. Recreate brand with performance image. Basically what Pontiac should've been. Use it as a playground for making oddball stuff without affecting core-brand image.
*Maruader 4-door based on Falcon XR8
*Capri as new lightweight RWD 2+2 using modified 2.3T from Mazdaspeed3 and fresh-sheet chassis emphasizing light-weight.
*Cougar as 2-door based on Falcon XR6
*Lynx as Fiesta with a manually-controllable version of the DSG currently used as the Fiesta's autobox and AWD.