Andy Hollis
Andy Hollis
4/20/15 11:08 a.m.

There is no denying the popularity of SCCA’s Street Touring category among the cone-dodging crowd. These street-friendly autocross classes continuously draw the largest fields, while others shrink.

Another option has been added to the card for 2012: Street Touring FWD—a new class for mildly modified, front-wheel-drive machines.

So which horse do you bet on? A head-to-head comparison test between the contenders would be ideal, but that requires some development time—plus the money to set up each car.

In the past, we have successfully used a shortcut: spreadsheets combined with a little intuition and background knowledge. Two years ago, we performed this exercise when the SCCA unveiled Street Touring Roadster, a similar class for fast, late-model convertibles. By analyzing the strengths and weaknesses of each of the eligible vehicles, we were able to successfully predict some winners.

A Little From Column B

Originally introduced in 1998 as an experiment, the Street Touring class was designed to attract the sport compact crowd from the street scene to the autocross course. The target vehicles were four-seat sedans and hatchbacks with small four-cylinder engines, and the allowed modifications included the typical bolt-on engine and suspension goodies.

The other key ingredient was the use of real street tires. The SCCA’s goal was to facilitate an arrive-and-drive type of experience—no second set of wheels mounted with dedicated race tires.

Whether that message reached the target market is debatable, but there is no doubt that the formula has become attractive among existing competitors. Recognizing this, the rule makers eventually added classes targeting other vehicle types popular within the SCCA ranks.

In 2002, Street Touring X was formed around the then-new Subaru Impreza WRX as well as rear-drive pony cars like the Mustang. The BMW 3 Series added some spice to the mix.

When the Subaru STi and Mitsubishi Evolution überboost buggies arrived in 2004, they were given their own playground in Street Touring Unlimited. High-performance sedans and coupes like the BMW M3 also joined the fray.

At the same time, older two-seaters like the early Mazda Miata and Honda CRX set up camp in STS2, later renamed STS. Finally, in 2010, STR became the home for the faster, more modern two-seaters already in the garages of many SCCA members—cars like the Honda S2000, Mazda MX-5 and Toyota MR2 Spyder.

As the original class within the category, the recently renamed Street Touring C has had the longest time for development. Veteran participants have carefully sifted through the eligible cars to find the one single model that best takes advantage of all the allowed modifications: the 1989 Honda Civic Si.

A large part of that advantage comes from the era in which that car was built, as this model predates airbags as well as the excessive comforts and conveniences that weigh down many of today’s cars. As a result, that 1989 Civic Si is light, weighing 700 pounds less than today’s version. When you’re asking a car to change directions, excess weight is the last thing you want, no matter how much power is under the hood.

Rather than ban an overdog, the SCCA has created STF as a place for newer front-drivers that just can’t out-handle the 1989 Civic Si. There isn’t anything more than 10 years old in the new class, and the focus is on the new B-segment microcars, like the Honda Fit, Ford Fiesta, Mazda2 and Fiat 500. Slightly larger front-drivers like the MINI Cooper, Acura RSX, Toyota Corolla and Scion tC are also invited. Strict tire and wheel limits—a 225mm tire on a 7.5-inch rim—have been mandated in an attempt to level the playing field between the smaller, lighter cars and the ones with more power.

Once again, there’s potential for big fields, as many enthusiasts already own these cars. They deliver great fuel economy and make excellent daily drivers. And with a few suspension and engine mods, they can deliver lots of fun between the cones. Which ones are potential winners? Let’s crunch some numbers to see.

Finding a Front Runner

As we did in our STR analysis, we worked from factory specs to generate theoretical performance indicators for this test. They help us understand a car’s strengths and weaknesses. Acceleration (thrust factor, in our formula) is important, but handling is the real key. We’ve found that the ratio of vehicle weight to tread width (grip factor) is a good predictor of that.

We also looked for any Achilles’ heel that could cripple a car—you know, something that could knock a seemingly top contender from competition. On the other hand, we also looked for things that could make a vehicle greater than the sum of its parts.

Our methods got a tweak this time around, however. In the past, we have made grip equal to three times the weight of acceleration. Since we have noticed more national-level courses with slower turns, we think a 2:1 factor might be better in some instances. We calculated our figures twice: once with each factor.

At the moment, the prevailing wisdom among top contenders—backed up by our own testing—is that the best tires for dry-weather autocrossing in the Street Touring category are either the Toyo Proxes R1R or the Hankook Ventus R-S3.

However, these two tires aren’t available in the optimal sizes for each analyzed vehicle, so we had to make some compromises and assumptions. For each car, we selected the best candidate—the tire that provides the best gearing and most stick. That meant the 195/50R15 Toyo for the lighter cars and the 225/45R15 Hankook for the heavier ones. Cars with shorter gearing needed to upsize to the 215/45R17 or 225/50R16 to avoid constant shifting. Now, on to the contestants.

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