Cars similar to the Lexus ES300 and Crown Ford victoria?

I'm looking for a car that is built like a tank or rides smooth. Gets good gas mileage and is reliable.

Your question implies that you think a Lexus ES and a Crown Vic are similar, they really are not. One is a mid sized FWD sedan with a unibody, the other is a RWD full sized body on frame car. They are very different vehicles. The ES is really just a rebodied Camry.

If you want a large solid sedan You can go to Impala, Avalon, Taurus - many choices. Nothing really left like the Crown Vic though, unless you buy a nice clean used one, they are fairly inexpensive. Note the Mercury Grand Marquis and Lincoln Town Car are pretty much the same vehicle.

Cadillac Deville

An ES300 is the same platform as a Camry. The Crown Victoria shares a platform with the Mercury Grand Marquis and a Lincoln Towncar. Sharing a platform means the suspension and mechanical underpinnings are identical and it should basically ride the same.