I have a 94 Lincoln Town Car. It is essentially the same car as a Ford Crown Vic.
It has 194K miles on it and it has not had a major failure.
It uses a quart of oil to 4500 miles. Not bad.
It runs and drives like new.
Taxi companies buy old cop cars and run them as taxis.
They routinely run them to 400K miles without replacing the engine.
I've read that limo companies in NYC routinely run new Town Cars 750K+ miles. They change the oil every 2000 - 3000 miles and aggressively maintain the cars.
Ever since GM stopped making the Chevy Caprice, Ford is the only manufacturer who still offers the large rear wheel drive sedan.
Have you ever had the valve seals replaced? It's a relatively cheap procedure and might be the cause of your oil consumption. It was a known flaw in that era.
The Crown Vic drivetrain is wellnigh indestructible with regular maintenance.
..No Doubt, for the higher priced autos (like LEO cars.), but for lower priced...one word: pinto/chevette/hornet :))