When the Coca-Cola 125 Raceway opens Friday, drivers of all ages - provided they're at least 7 years old and tall enough to reach both the steering wheel and brakes - will be able to experience the thrill of stock car racing in miniature. It's a go-cart track, of course, the latest in The Clubhouse's offerings of family-oriented activities that already include bowling, highly interactive electronic games, laser tag, golf and batting practice, miniature golf and mini-bowling. Darin and Netra Van Tassell, owners of The Clubhouse, hope to see a crowd Friday for the first day of racing.