Just worth mentioning..don’t get confused what the phrase is. You asked if we use “ any colour as long as it is black” You need to look at “as long as” only Mr Ford used it in a joking way as the T model was in such a demand and they were trying to ramp up the production so the only colour available was black. Otherwise you set the conditions in any way….. You can wear anything to our company’s event, as long as you look smart. Ok, I will drop you off, as long as you pay for the petrol.

Yes, I've heard it, but I can't think of any specific examples. It was an intentional joke by Ford, it is a humorous way of saying "there is no choice." If someone is told there is no choice, they might say, "Oh, I can get any color I like as long as it's black, eh?" Tanya's examples are realistic. As a matter of historical fact, it wasn't strictly true. Although there was a period of time during which they were only produced in black, they were produced in other colors, too. Ford did it that way for reasons of production economy, not because he wanted to deny choice to his customers. Paint technology wasn't what it is today. Black was durable and economical. And the other colors that could be produced at the time were rather dark and dull.

I agree with Lenka. It's a joke. The sentence "any customer ... as long as it's black" contains a contradiction. It is not possible for the customer to have any color he wants, and also to require that that color be black. So Mr. Ford was saying "you have to want what I want", which either means that he was a jerk, or that he was making a joke. Don't let anybody stop you from writing "colour". That's the British spelling, and perfectly acceptable. It's probably best to be consistent, though. If you decide to use British spellings, try to do it consistently.

Also, It’s color. Colour is British.

I've heard it used in a joking way eg. A shopkeeper only has pink cupcakes left, "you can any colour you like as long as its pink" or only vanilla ice cream is available "you can have any flavour you like as long as its vanilla"