I know that Ford and Mazda were working jointly when our cars were made, and I read somewhere that the Focus uses the same platform as other Mazda cars. I was just wondering if that means there are any interchangeable parts from a Mazda to put on the Focus? If so what Mazda cars use the same platform as the Focus?
Depending on the era, they share a very large number of parts. Ford sold off their controlling interest in Mazda in 2008, and reduced further in 2010. I feel it was a bad decision and harmed both, considering Ford's newer engines are descended almost completely from Mazda's engines. Ford, Mazda, and Volvo jointly developed the C1 platform in 2003. Volvos from that era also have numerous Ford-branded parts.
Having driven both, I personally believe the Mazdas of the era had much better suspension/tuning and that all three gained considerably from combined effort. Mazda has probably suffered the most after the split... They do share some tech, but no parts anymore.
http://en.wikipedia.org/wiki/Ford_C1_platform
Note the long list of cars on the platform. The closest cars in Mazda's lineup are the 3 and 5.
Take off nearly any part on a Mazda and it may read fomoco. Ford gave Mazda keys to their parts bins and Mazda went nuts. Ford spent millions on engineering and Mazda got the likes of the speed3 out of the deal. But that's fords m.o. Of waiting and bringing us the best. They didn't go bankrupt for a reason.
I wouldn't describe it like that. A lot (and I mean a lot) of parts on small Ford cars over the years were directly from Mazda, especially drivetrain components.
My Ford ZX2 was essentially a shortened Mazda Protégé with a different body, interior, and engine. It was the spiritual successor to the Ford Probe, which was even more of a Mazda the further you go back - the original was practically a rebadge, considering even the engine and many exterior components of the car were directly from Mazda.
It's one of the sadder results of the recession. A very long and successful collaborative partnership was lost.