Which used Lexus GS saloon should I buy?
Go for the cheapest model. There's not as much of a difference as you'd think between the 3.0 V6 and the 4.3 V8, and the smaller engine suits the car's relaxed nature best.
Alternatively, the petrol-electric hybrid GS450h teams a 286bhp petrol engine with a 190bhp electric one. It's a clever device and amazingly rapid, but its 35.8mpg overall isn't frugal enough to make it sensibly eco-friendly, or even sensible.