CVT Transmissions: Pros, Cons, and Why They Divide Opinions

CVT has become one of the most polarizing terms in automotive culture. This acronym has become synonymous with “uninspiring,” and both die-hard manual transmission enthusiasts and casual drivers alike tend to dislike vehicles equipped with these transmissions. But is this sentiment truly justified, or do CVTs deserve more respect?

Regardless, CVT transmissions have become ubiquitous in the automotive market. Once confined to small, inexpensive cars, they’ve made their way into full-size sedans and SUVs. Even performance cars like the Subaru WRX now offer CVT options, and many hybrid vehicles utilize e-CVT systems that combine the power of both gasoline and electric motors on a single output shaft. Love them or hate them, CVTs are here to stay.

How CVT Transmissions Work

To understand why CVTs are so divisive, we need to compare them to traditional automatic transmissions. Unlike conventional automatic transmissions with multiple gear ratios, CVTs have no physical gear. Instead, they rely on two pulleys and a belt to transfer power from the engine to the wheels. One pulley is connected to the engine crankshaft (the drive pulley) and the other to the driveshaft (the driven pulley).

These pulleys consist of two cones that face each other. These cones, controlled hydraulically, can move closer together or farther apart. At low speeds, the cones of the drive pulley are spread as far apart as possible, allowing the belt to ride on the smallest diameter. Simultaneously, the cones of the driven pulley are close together, causing the belt to ride on the largest diameter. This provides maximum torque at low speeds, similar to first gear in a conventional automatic transmission.

As speed increases, the cones of the drive pulley move closer together, and the cones of the driven pulley move farther apart. This causes the belt to climb up the drive pulley and down the driven pulley, resulting in a higher gear ratio and lower engine speed at higher vehicle speeds. Early CVT designs only had variable drive pulleys, but modern CVTs feature variable driven pulleys as well, allowing for a wider range of gear ratios.

History of CVT Transmissions

CVT transmissions predate the automobile. While Benz Motorwagen used a rudimentary CVT with a belt and pulleys, the first production car with a CVT was the 1923 British Klein. However, early CVTs had limited power-handling capabilities, and Klein’s success was primarily in small, low-powered motorcycles.

It took several decades for CVTs to gain traction in the automotive industry. In 1958, the Dutch company DAF, now known for its trucks, introduced the 600, a small city car with a continuously variable transmission called the Variomatic. This early CVT used large pulleys and a rubber belt and was integrated into the rear axle. While the belt was prone to wear, the 590cc air-cooled engine with only 22 horsepower didn’t put excessive strain on the transmission.

The 600 was a commercial success in Europe due to its fuel efficiency and compact size. It was even sold in limited numbers in the United States in the 1960s, but a legal restriction prohibiting vehicles without a park position limited its success. It wasn’t until the 1989 Subaru Justy that Americans could experience a more modern CVT. This CVT was more advanced and could handle significantly more power. Thanks to computer-aided design and advancements in materials science, modern CVTs can achieve transmission efficiencies of over 90%, compared to around 85% for conventional automatic transmissions.

Why Do People Dislike CVTs?

Despite their advantages, CVTs still have their detractors. One common complaint is the constant engine RPM during acceleration. While this contributes to fuel efficiency, it can create a monotonous and uninspiring driving experience. Some manufacturers have addressed this by programming their CVTs to simulate gear shifts, providing a more traditional driving feel. Some vehicles, like the Subaru WRX, even offer manual shift modes using paddle shifters. This allows manufacturers to retain the benefits of CVTs in terms of fuel economy and cost while providing a more engaging driving experience.