Steve Baur
Former Editor, Modified Mustangs & Fords
December 29, 2004

Spanning the globe to bring you a constant variety of sports." These were the words of Jim McKay and they were heard at the beginning of every Wide World of Sports broadcast. Here at MM&FF, we are always looking to bring you exciting stories other than drag racing, and we think we've found one with Carol Hollfelder and her Tiger Racing Speed World Challenge GT Mustang.

This story begins with a young Carol Hollfelder, a resident of California and avid equestrian. Carol competed on horseback for nine years until she injured her spinal cord in a motorcycle accident at the age of 18. With her horseback riding days behind her, Carol found a new hobby that included horses of a different sort.

Carol's parents, Tom and Bea Hollfelder, had started collecting vintage automobiles when Carol was just a toddler, so she had been raised around cars and road racing as well--both of her parents also participated in vintage racing events. In fact, Tiger Racing got its name from the Sunbeam Tiger that Bea drove.

Getting started for Carol was as easy as slipping behind the wheel of her Toyota Supra and entering club events and then races. She eventually stepped up to a Ferrari Challenge car, which was basically a race-prepped F355 street car. The Speed World Challenge class was her first foray into professional racing, and Carol found that the sports car with the prancing horse on it wasn't so competitive. That prompted the decision to build a new car. It too wore a pony on its paint, but this horse didn't just prance, it galloped.

HP Motorsport of Omaha, Nebraska, took a body-in-white Mustang from Ford and transformed it into a full tilt racecar. Building off a chrome-moly tubular front crossmember, HP bolted on the HPM/Bart double A-arm suspension using Bill Watkins spindles and Koni double adjustable coilovers with Eibach springs. Brembo six-piston calipers were used to clamp down on the pizza pan-like 14-inch rotors, which fit neatly inside Fikse three-piece forged aluminum wheels wearing Toyo Proxes RA-1 275/35/18 rubber.

Out back one will find a Dana 44 chunk amid an IRS setup, and a Quaife differential with a 3.89:1 ring and pinion gets the 335/30x18 Toyo meats rolling. Koni and Eibach coilovers can be found here as well, and Brembo four-piston calipers are employed with 13-inch rotors.

The firewall was set back 4 inches to better distribute the weight of the four-cam Modular powerplant that pumps out an estimated 500-plus hp. A stock Cobra crankshaft swings Manley rods and Mod Max pistons in the short-block, while the Ford four-valve heads were treated to a Mod Max valve and spring package and Mod Max Stage 1 Street camshafts. The intake manifold is the FR500 unit from Ford Racing, and the 80mm throttle body has been adapted for drive-by-wire operation. The big power comes from a Vortech T-trim supercharger set (by class rules) for 10 psi of boost, and it works with Vortech's air-to-water Aftercooler.

Bassani headers dump into a custom X-pipe that terminates out the sides of the car right before the rear wheels. The ignition is stock Ford electronics, but the fuel system is by Aeromotive and the oil control system is a high-end AVIAID five-stage dry sump setup.

Since Carol isn't able to shift and clutch a manual transmission, an alternative was found with help from Ford Advanced Powertrain. The transmission is a T56 six-speed that has been modified with the addition of the auto shift manual/select shift manual system from the Aston Martin Vanquish.

The ASM/SSM system is essentially an electro-hydraulic control for the transmission that is actuated by two buttons located on the steering wheel. The high-tech controls don't end there though, as the steering wheel is a telescopic unit that applies the brakes when forward pressure is applied to the wheel. A metal ring rotating on bearings and mounted 2 inches behind the steering wheel is the throttle control. To give it gas, simply squeeze or pull the ring toward you. Many of these controls were perfected on Carol's F355, and her father, Tom, and Steele Therkleson, a mechanic on the legendary Ford GT40 team of the '60s, designed and fabricated them. Think you've got it tough heel and toe downshifting? Try doing three separate things with just two hands.

HP Motorsport TIG-welded a custom chrome-moly rollcage for the car, and then installed a Schroth six-point harness and a BRITS Inc. AFFF fire-suppression system. Carol's seat for the duration of each race is made by Kirkey and features a Nomex cover. HPM also designed the custom dashboard and control panels that use Auto Meter gauges and Stack data acquisition. The steering wheel is a modified MOMO unit that is connected to a steering quickener gearbox.

Paul Brown of HPM put some preliminary laps on the car before Carol actually drove it, but with nearly twice the horsepower of her Ferrari and completely different handling characteristics due to the difference in drivetrain layouts, there was quite a learning curve, especially since her first race of the season was just a week away.

Paul was brought on as general manager and crewchief for the Tiger Racing team, and the Mustang's 2003 season has been a year of working out new car bugs. But, Carol cruised to a 15-place finish at Road Atlanta this year, and the car keeps getting better and better.


Ford Motor Company is supplying the Tiger Racing Mustang with the 4.6-liter engine as part of its "No Boundaries" campaign. The engines are rebuilt so they would stand up to the rigors of road racing, which includes far more abuse than just a quarter-mile pass. Notice the unique Aftercooler placement required for use with the FR500 intake manifold.
The body-in-white Mustang received a lightened '03 Cobra hood, an '03 Cobra rear bumper cover and an '03 front bumper cover that was mated to a Tiger Racing front splitter. The yellow head light lenses are for the American Le Mans Series GT class.
This is one high-tech advanced Mustang. Drive-by-wire technology is employed on the throttle, where a ring mounted behind the steering wheel is squeezed to accelerate. Throttle position can be maintained throughout the turning radius thanks to its inherent design. The transmission is shifted via two buttons that are mounted on the steering wheel.
The Mustang's racy paint job is the design of Nicholas Greene, a student at the Pasadena Art School of Design. Autokraft in Lincoln, Nebraska, applied the paint.
Carol Hollfelder brings quite a bit of racing experience to the Tiger Racing team, having run her Ferrari F355 challenge series in 1998 and SCCA club events in 1999 before debuting in the Speed World Challenge series in 2001. In order to be competitive in the series, Carol traded in her Italian stallion for an American thoroughbred.
Vortech Superchargers is one of Tiger Racing's sponsors and helped out with this T-trim unit. The World Challenge class rules limit maximum boost to just 10 psi.
Finally a car with a big wing that actually has a mechanical purpose. With over 500 hp on tap, high speeds are easy to attain and the HPM 9006AC carbon fiber wing does a good job of planting the tires to the pavement.