Before I start, let me define some things:
"Best Overall" - This includes best in all categories, not just sports/super cars.
"Major" - Since GM owns Saab, you can use Saab to support of your argument for that GM is the best company, for example.
This is retroactive btw, so despite Jaguar not being owned by Ford in the 60's, those cars are still game.
Now, at risk of being flamed off the board, I'm gonna say Ford is the best overall company and this is why:
Every day car
They've got the best "every day" cars out there, thanks to Mazda. The Mazda 3 is a blast to drive when loaded with the 160 bhp engine. They've also got an excellent sedan with the 6 series. Mazdas also refuse to break down no matter how much you abuse them and also get great mileage (My first car, a 95 protege, was in 6 crashes thanks to my sister, 3 of them major and STILL ran without a hitch. My mpg on long trips was usually in the mid 40's, manual transmission)
The Mazda3 is now gaining a large aftermarket and consequently i'm seeing more people to the rice hell out of.
Mazda sells well in both America an Japan (I'm not sure about Europe)
...and for Europe we got the Ford Focus. Good car, popular as hell, decent mpg and crash test.
Low-end Sports Car (Under $40k)
We've got a couple of here:
Let's get the obvious ones out of the way straight up:
Mustang V6/GT/Cobra - Good engine, good looks (IMO), and a hell of a lot of history. Most American boy's dream car in highschool, especially with the muscle car appeal. Best sound from their engines IMO also.
Mazda Miata - Small, sporty, convertible, and cheap. I would never drive one, but I know plenty who would.
Mazda RX-8 - The only acceptible 4-door sporty car. Good handling, looks good, etc.
Performance Cars
Ford Focus - I add this here because of it's rally abilities. It's a dominant factor in in such races, thus deserves a spot under performance cars.
For "European" appeal, we've got the DB9... need I say more? Refined, fast as hell, and beautiful.
Ford GT - Also beautiful, awesome performance, but not as fast as...
Jaguar XJ220 - Not the fastest street legal car in the world anymore, but still ridiculously speedy. Handling, breaking, power... it's got it all
Luxury cars
Can you say Jaguar XJ-series? Luxurious, prestigious, and perfect for those who have much more money than I do.
History
I don't think anyone can argue that Ford doesn't have an impressive history, dating back to the turn of the 20th century.
Jaguar also has a decent history, going back to around the 50's and has definate pedigree.
Racing wise they've had a fair amount of success, as anyone who has ever heard of the GT40 and knows anything about the Le Mans has to give it props for 4 years of 1st place victories (66,67,68,69)
Iconically, Ford boasts several cars with history also:
Shelby Fastbacks - While not strictly a Ford company, it's Ford VINs they stick on the new models, so I'm gonna count it.
GT - Already Explained
1957 Jaguar Roadster - YES. Luxury car anyone? Also is very beautiful.
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Alright, I'm done...
What you got for me?