The sole purpose of any company is to make a profit.

A good car company:

Quality of build: combine Rolls Royce and Aston Martin
Parts availability: add GM
Price of Parts: Your local auto parts store
Service quality: add Rolls Royce, Aston Martin, Mercedes, and BMW, Volvo, Audi
Selection of vehicles: add GM, Toyota, and Honda
Price of vehicles: Add Saturn
Durability: Ford trucks, BMW, Volvo, Mercedes
Warranty: BMW, Volvo, ? (fill in with your choice)


Qualities to leave out:

Expensive to repair: Rolls Royce, BMW, Mercedes, Aston Martin
Hard to find decent tires for: Any company
Expensive to purchase: See expensive to repair
Cheap in quality: Hyundai, Kia, Most American born companies (they don't have the quality standards that foreign companies do ...Honda, Toyota)

I think that a combination of companies would work best, but that may never happen.

It all comes down to money. Whoever has the most, gets to choose.