Success doesn’t always lead up. Look at the Porsche 911, a model so steeped in tradition that any attempt to advance away from deeply rooted idiosyncrasies is met by derision and then depression from the fanbase.

Okay, bad example, because the 911 didn’t sell in a million examples through anything other than success in many forms, but the point is sometimes the right formula doesn’t work in every application. When a car is a hit, you have to learn to draw the milking line.

Everyone loves the Mazda MX-5, but if the customer complained that it isn’t very good off-road, the engineers shouldn’t rectify that complaint with an off-roading MX-5 (on the other hand, hmm…) because that isn’t what an MX-5 is.

Oftentimes in the car world, a successful model rides its sales wave too far out and becomes something it never set out to be. A Golf GTI is nowadays far from a tinny little runabout. Since inception in the Seventies the Golf has long forgotten what it was and stepped upmarket twice, first replaced by the Polo and now by the up!. Everyone has examples.

Ford has one of the best. In the Fifties, the Thunderbird was a movie star car, Ford’s Corvette and the belle of every ball. It was a two-door, two-seater halo vehicle and kept on riding boulevards as a rolling Blue Oval ambassador until some marketing men in the Sixties decided to make the customer a little too right. They wanted more space, they said, more doors… Ford gave it to them and made a four-door T-Bird in 1967 that was so successful they killed it off in 1971 never to return… Anyone else that wanted a four-door T-Bird just bought a Lincoln. Ford solved a problem that didn’t exist and tarred the T-Bird in the process.