Pitting a Porsche-hunting FrankenSubie against the Viper: Motoramic TV

There are two problems with kit cars: tracking down all the necessary parts can be a pain, and the all-in cost can become prohibitively expensive, once you factor in paint and oddball parts. The solution, the holy grail of do-it-yourself car-building, is the “single donor” approach. With a single-donor project, you buy the kit plus a complete used donor car, then spend some quality time in the garage fusing the two of them into something new and wonderful—no further parts-sleuthing required. That’s the ideal. And that’s the premise behind the Factory Five 818.

Find yourself a wrecked or exceptionally ugly 2002-2007 Subaru WRX, unpack Factory Five’s body and chassis and then use the WRX guts to build a lightweight little two-seater with turbocharged flat-four power. The finished weight ends up at 1,800 lbs. (818 kilograms, hence the name), which means that even a stock 265-hp Subaru 2.5-liter motor will provide serious speed. The kit costs about $10,000, so the target price for a finished car is $15,000. The price depends on how cheap you can score a decent WRX (and how adept you are at selling off unused parts, like the body shell).

The 818 is available in street and track versions, the 818S and 818R. I drove the street-legal S version on the top secret Yahoo! Autos test runway, and I can’t imagine how much of a lunatic you’d need to be to go for the R. As it is, the S feels quite track-ready, with its feathery weight, unassisted steering and bombastic flat four thumping away from the strangest of places—behind you. It’s a minimalist experience, but if you need creature comforts, you can always buy a well-used Porsche Boxster S. A car that, incidentally, the 818S will likely stomp in any performance category you’d care to name.

When you’ve got WRX power paired with the weight of a Smart car, it’s hard to find much competition at anywhere near the 818’s price. Which is why we brought in something that costs a little bit more. OK, a lot more: a $142,000 2013 SRT Viper GTS. No, it’s not a fair fight. But can Factory Five’s little roadster hang in there with one of the biggest bullies on the road, a car that might well cost 10 times as much? Let’s drop the clutch and find out.