[Bicycle Bob]

My favourite would be the XFI model from the early 90s. That body is significantly slimmer and lighter than the later models with OBD II, but those engines all have EFI and on-board diganostics. The XFI 3-cyl (with all-black bumpers) had the highest final drive (also available on the 8-valve) and a high-economy camshaft, plus other tweaks for mileage. The base model had body-colour bumper tops, and the luxury model's bumpers are all coloured. The exhaust valves are prone to burning, but are easily replaced. See "Sam's Method" on the Metro forum archives. Apart from the Achilles heel of rusted suspension mounts, they are as durable as Toyotas - one guy ran a fleet of dozens of them for deliveries in NYC, and got a quarter million miles out of each.
For years, I was put off by the prospect of a 3-cyl engine, but it is more efficient, and unlike a 4-cyl, it does not stop all the pistons at once. It is one of the lightest cars available; well under a ton, and it goes well in bad weather until high-centered. The optional 13" wheels help with that and raise the gearing too. Prices quadrupled early last year, but there are some bargains re-appearing.