[oldE]

I would have to say early 70s.

Prior to that the engineering that went into the cars was unique within GM. They had their own motors, chassis and drive train.
If you had to travel long distances and could afford it, you got a Caddy. No question.

One of my brothers worked in the DEW Line in the 60s and 70s. Through the years he had iirc a '58 (green, two tone, auto dimming lights), a '63, a '66 (bronze with leather) and a 68. Those cars would cover an amazing distance with a family in comfort, even over winding two lane roads.

When GM changed the bodies to meet the bumper laws in '72 and '73, I suspect the engineering was done for most large models across the board. The cars started to go downhill then: rattles, loose pieces cheaper interiors. By the time the cars were 'downsized' they were squeezing every $ out of the car they could. It ceased to be the "standard of the World" and became a travesty.

The Eldorado was a re-skinned Toronado, the Seville somebody's idea of a joke and the Cimmaron an insult.

I have been pleased to see CTS and STS sedans (plus the V versions of both) and the XLR. On one hand, they are based upon chassis which originated within other GM divisions (Opel and Corvette), but they seem to be trying to give the cars their own identity.

Too bad there was 30 years of neglect.

Les