NASCAR only allows five-speed transmissions - but why?

In the world of motorsports, few racing series and genres in this day and age of technological leaps and bounds have managed to strike a balance between the new and the old like NASCAR has. Boasting one of the fastest yet one of the most analog-to-drive cars in the history of the sport and motorsports in general, stock car racing in general has always been known to keep in touch with its roots.

Ever since the 1940s, there have been many changes concerning safety in NASCAR. However, a few technical aspects of the stock car as we know it today have remained the same for more than half a century. Up until the sixth generation NASCAR Cup Series car, which saw its last race in the 2021 season, the highest echelon in the sport mandated the use of 4-speed H-pattern manual gearboxes.

Based on a Ford-designed gearbox from the 1950s, a derivative of the same was used in Cup Series cars until 2021. H-pattern-shifting and 4 individual gears meant the race cars were ever so similar to their road-going counterparts, a notion that rapidly diminished over the last two decades of the sport.

With the introduction of the seventh generation Next Gen car, the governing body switched the age-old recipe of the 4-speed gearbox to a new Xtrac P1334 5-speed sequential transaxle. What that means is that the new gearbox manufactured by Xtrac has five individual gears, ditches the H-pattern in favor of a sequential up/down shifting action, and is now integrated into the rear of the car instead of being mated directly to the engine.

The switch to a 5-speed unit was as close as NASCAR could get to modern times without going to paddle-shift style automatic gearboxes, which would ruin the stock car's traditional feel while keeping it somewhat relatable to road cars. It's a shame, however, that most cars in the United States of America today are automatic.

---

Why does NASCAR only allow manual transmission?

Unlike faster-shifting and technologically advanced paddle-shift gearboxes, manual shifters require a certain amount of effort on the drivers' part, which makes the person behind the wheel even more important than ever. Being in tune with the car and shifting correctly while racing on the track is vital to achieving success in stock car racing as automatics are unlikely to be introduced in the sport.

Unlike the Cup Series, the junior Xfinity Series and the Truck Series still use the old-school-style H-pattern 4-speed gearbox in their cars.