Cadillac = some really different engineering. It seems overly complicated to me but the ones I have had were damn good cars and I have been able to figure out whatever goes wrong and repair it pretty cheap. They seem to be as reliable as anything else out there as long as you don't let the problems stack up. No diagnostic equipment needed, it's built in.
A friend has an antique. I think it's like a 1930 or so business coupe. Ceramic coated exhaust system, dual mode suspension etc. All stock. I personally stood a nickel on edge on the engine while it was running and i didn't fall over. It makes no sound while running at any rpm.
I'm really glad that used Cadillacs don't have a big following. It's nice to have someone else take the big hit on a $45000 car and they really are a pleasure to drive. I figure, if I have to travel in a car it may as well be a Cadi.