The digital revolution has been transforming the auto industry for more than two decades.

Now it is taking the aftermarket by storm, speeding time to market and improving quality just as it has for OEMs and their traditional factory suppliers.

Only a few years ago, enthusiasts who wanted to customize a brand-new vehicle's body or engine often had to wait a full model year before parts were available. Even then, there was a chance they might not fit properly. Now, just about every custom part imaginable — from spoilers to specially calibrated engine control modules — are available as soon as a new vehicle hits dealer showrooms.

Most of the credit goes to the Specialty Equipment Market Assn.'s Technology Transfer program. Implemented in 1999, it allows its 6,000 member companies to access 3-dimensional and 2-dimensional computer-aided design (CAD) files of new vehicles three to six months before they are introduced.

The precise math data enables suppliers to create custom parts that match up perfectly with the surfaces or structural hard points of the new model.

Prior to the introduction of the SEMA program, suppliers had to obtain access to a production vehicle and then painstakingly measure and reverse-engineer components to get the information and dimensional data they needed to create a new part.

Users of the technology transfer program say it has shaved four to six months off their product development times and is creating higher quality parts that fit better.

Suppliers of specialty equipment (they prefer not to be lumped under the “aftermarket” umbrella) such as custom wheels, and appearance and performance parts, used to be an afterthought to most auto makers. Now, in an era where these suppliers sell almost $30 billion worth of parts annually in the U.S. and many enthusiasts choose new vehicles based on which one can be customized most easily, aftermarket suppliers suddenly have become key players in OEM marketing strategies.

Far from ignoring the specialty parts sellers and their customers, auto makers now fight for their affection at events such as SEMA's giant show each fall in Las Vegas. Being labeled “accessory friendly” is a treasured title. Both Ford Motor Co. and General Motors Corp. have had major press events and special vehicle introductions at SEMA in recent years. Honda Motor Co. Ltd. is crowing that this year it will be the first importer ever to be the official vehicle manufacturer of the SEMA show.

In other words, auto makers have realized if they don't cater to the so-called “tuner crowd” and make available dozens of performance and appearance add-ons for a new model the minute it hits dealer showrooms, thousands of key new sales could be lost forever.

A stark example is the Honda Civic. A perennial sales leader in the subcompact market and a favorite of young enthusiasts, sales drooped after the new '01 model was introduced, in part because its styling and front suspension layout wasn't “tuner friendly.” For one, the '01 model abandoned the previous model's double-wishbone independent front suspension for a more conventional MacPherson strut configuration. That cost-saving move made its handling less responsive than previous versions, critics say.

Honda is vowing to change that with the introduction of the '06 Civic in the fall.

“We do care a lot (about pleasing the enthusiast crowd),” Tom Elliott, executive vice president-American Honda Motor Co. Inc., told reporters earlier this year. “Honda's always had a very good presence among young buyers. We lost a little of that with the '01 Civic, mainly (on) the coupe side, which came across perhaps as a little bland.”

Engineers promise the new model is the best-handling Civic the company has ever produced but won't say whether the suspension has been changed back to a double wishbone.

On the other hand, Toyota Motor Corp.'s Scion youth brand is enjoying an enormously successful launch in North America, in no small measure because it is emphasizing customization features. The boxy xB is especially popular with tuners, says Scion's Steve Hatanaka. As Scion's accessory project manager, Hatanaka spearheaded the Toyota Div.'s participation in the SEMA technology transfer initiative in 2003.

Despite the importance of the customization industry, bridging the digital divide between auto makers and these specialty suppliers — many of whom are small — was no simple task. Before auto makers agreed to turn over tightly guarded computer models of a new vehicle's critical components six months prior to launch, numerous concerns about security and the ability of the companies to handle the data had to be addressed.

Ford was the first to see the value in working with SEMA on data transfer, and collaborated with the organization in a pilot program in 1999. It started by offering data for the next model-year Mustang.

“We released CAD data and surface data on the Mustang for the entire vehicle, everything from suspension, body, to engine, transmission…the whole thing was provided to SEMA members,” says Bob Adams, who oversees Ford's global auto shows and events.

When that pilot project succeeded, Ford moved on to a 2-phase program that included working with suppliers to develop unique calibrations for high-performance control modules that accommodate new parameters for supercharger packages, new axle ratios and other changes — while still ensuring the ability to meet 50-state emissions requirements.

Those projects have been so successful, Ford's involvement with the technology-transfer program now encompasses virtually all Ford, Lincoln and Mercury products, says Warren Nally, who supervises the auto maker's Aftermarket Support Group.

While much data now is shared, Nally warns, “There is a limit to the type of information we give out,” and says much of the engine still is considered proprietary real estate.

Once Ford broke the ice, SEMA says GM joined the program in 2001 and the Chrysler Group started participating in 2002. Scion was the first Asian brand to join in 2003.

With SEMA acting as a buffer, it appears aftermarket suppliers and OEMs are avoiding some of the hassles encountered in more traditional data exchange arrangements.

Highly sensitive to security issues and worries about part counterfeiters stealing the data, SEMA screens all the supplier participants (who already are SEMA members) and is responsible for distributing the CAD data files. It has a strict enrollment process and rules that ensure auto makers' intellectual property is protected. OEMs say the organization has allayed their security concerns.

Software and hardware issues also have been minimized. For instance, traditional factory suppliers usually have to make considerable hardware, software and training investments to accommodate the specific requirements of each auto maker's computer engineering software. However, both Scion's Hatanaka and Ford's Adams say their math data is converted from their proprietary systems to a standardized Initial Graphics Exchange Specification (IGES) format that is easy to use.