A little over a year ago, I bought what could be the most interesting car I will ever own. It was a 1987 Mercury Sable LS station wagon. Don't worry – there's much more to this story.I've always had a soft spot for wagons, and I still remember just how revolutionary the Ford Taurus and Mercury Sable were back in the mid-1980s. As a teenager, I fell especially hard for the 220-horsepower 1989 Ford Taurus SHO – so much so that I'd go on to own a dozen over the next 20 years. And like many other quirky enthusiasts, I always wondered what a SHO station wagon would be like.That changed last year when I bought the aforementioned Sable LS wagon, festooned with the high-revving DOHC 3.0-liter V6 engine and five-speed manual transmission from a 1989 Taurus SHO. In addition, the wagon had SHO front seats, a SHO center console, and the 140-mph instrument cluster with mileage that matched the engine. When I bought it, that number was just under 60,000 – barely broken in for the overachieving Yamaha-sourced mill.The engine and transmission weren't the only upgrades. It wore dual-piston PBR brakes with the choice Eibach/Tokico suspension combo in front. The rear featured SHO disc brakes with MOOG cargo coils and Tokico shocks, resulting in a wagon that handled ridiculously well while still retaining a decent level of comfort and five-door functionality. I could attack the local switchbacks while rowing gears to a 7,000-rpm soundtrack just as easily as loading up on lumber at the hardware store.Over time I added a front tower brace to stiffen things a bit as well as a bigger, 73-mm mass airflow sensor for better breathing, and I sourced some inexpensive 2004 Taurus 16-inch five-spoke wheels, refinished in gunmetal to match the two-tone white/gunmetal finish on the car. That, along with some minor paint and body work, had me winning trophies at every car show in town.And yet, what I loved most about the car wasn't its looks or performance, but rather its history. And here's where things also get a little philosophical, because I absolutely, positively love old used cars . Don't get me wrong – new cars are great. Designers can sculpt a timeless automotive shape, and engineers can construct systems and subsystems to create an exquisite chassis with superb handling and plenty of horsepower. But it's the age and mileage that turn machines into something more than the sum of their parts. It's what gives terrible cars an endearing charm, and it turns great cars into legends.This Sable wagon was purchased used in 1990 by a mid-level Ford engineer in Dearborn, Michigan, who then also bought a wrecked 1989 Taurus SHO with 4,500 miles. It was strictly a personal project, but according to the stacks of paperwork that accompanied the wagon, no expenses – not to mention Ford resources – were spared in the build. I've seen a few SHO wagon conversions through the years, and they all had a feeling of being, well , a conversion. This one felt as though it was built on the assembly line to be a proper family-oriented performance machine.As evidence, the paperwork included numerous receipts for Ford parts, right down to Blue Oval nuts and bolts. There were copies of Ford blueprints from the Atlanta assembly plant outlining clutch updates and installations. Buried in this two-inch-thick folder, I found SHO engine flow charts, prototype designs for the rod-shifter update that all SHOs started receiving in 1991, and several hand-written notes on everything from valve adjustment procedures to melding the SHO brain with Sable wagon wiring. If Ford had ever officially built a factory five-speed SHO wagon, I truly believe it would have turned out just like this near-prototype.I can imagine this car cruising Woodward Avenue north of Detroit in the 1990s, driver and FoMoCo passengers lining up at traffic lights next to unsuspecting Mustangs and Camaros , just like they did in the late 1960s. By today's standards the wagon isn't terribly fast, but 20 years ago the shame and embarrassment of a pony car losing to a Sable wagon must have been epic.Nobody ever really knew about this car. Until now, hopefully. How many more car stories like this are out there? We need to know them. We need to share them.I spent a year with this Sable SHO wagon that could've been. I sold it just a couple months ago, because, let's face it, I have a used-car addiction to feed. I'm happy to say it lives on in California with an owner who's just as excited and fascinated by it as I continue to be.Yeah, I miss it. But I feel great having become a part of this car's unique history, and even better for sharing the story. Will it be the most interesting car I'll ever own? Possibly, but then again, there are many other used car adventures waiting to be discovered.