Honda Insights have been produced with a continuously variable transmission (CVT) instead of a conventional automatic transmission since their inception. A CVT bypasses the need for a fixed set of gears and instead operates with almost unlimited combinations of engine-speed-to-vehicle-speed ratios. While this improves fuel economy and performance, there are some disadvantages of a CVT when compared to manual transmissions and conventional automatics.
Disadvantages Compared to Manual Transmissions
The slightly larger size and heavier weight of the CVT transmission lowers the Insight's overall fuel efficiency. Insights with manual transmissions may expect to get 61mpg in city conditions and 68mpg during highway driving. Those numbers with a CVT dip to 57mpg in the city and 56mpg on the highway.
Revving and Noise
Because the CVT controls the car's engine differently than a traditional automatic transmission, drivers will notice changes in the way the engine behaves. The engine can rev at any speed, which can alarm drivers who are unused to this. The sound of the engine's varying speed can resemble that of an engine in a car with a slipping clutch or a sliding transmission. Cautious drivers who are unused to this effect may spend unnecessary time and money on unscheduled service checks due to what they believe are symptoms of a problem.
Misconceptions Over Acceleration and Power
A vehicle with a CVT accelerates more smoothly than a comparable vehicle with a conventional automatic transmission. A car with a manual transmission will jerk ahead slightly when it begins to move, but the CVT accelerates without any jerking sensation. The CVT also regulates engine speed as the car accelerates and decelerates. An engine attached to an automatic transmission will rev audibly as it accelerates, but the CVT may prevent this sound. These differences between the CVT and automatic transmission can present the illusion that the Insight lacks acceleration or power at higher speeds.
Early Horsepower Limitations
Early Honda Insights with CVTs were limited to low horsepower engines. The torque-handling capability of early CVTs was limited by their transmission medium. This was usually a belt or a chain, which experienced excessive wear due to friction from higher horsepower engines. More advanced and expensive CVTs have been developed with the use of advanced lubricants, and these may work with larger vehicles and engine sizes.
Lower Fuel Efficiency at Highway Speeds
The EPA rates Insights with CVTs at 57mpg in city driving conditions and 56mpg on the highway. It may seem counterintuitive for a vehicle to get better mileage while cruising than while constantly breaking and accelerating, but several factors contribute to this unusual trait of the Insight.
All engines burn less fuel when operating at lower speeds due to the smaller amount of work they have to do. Smaller gas engines, such as four-cylinder and three-cylinder car engines, are ideal for achieving high fuel economy at lower speeds, but they may begin to strain when maintaining the higher speeds of highway driving. This strain can counteract and even negatively impact a small engine's overall fuel efficiency while cruising at high speeds.
An Insight with a CVT operates with a total of 65 horsepower, or 71 horsepower with the electric motor assisting, which is somewhat less than the horsepower produced by a five-speed Insight with the same engine. The difference in horsepower and the additional weight of the CVT contribute to engine strain, which reduces engine efficiency.
The electric motor assist feature, which is largely responsible for the Insight's high city mileage, is usually not engaged at cruising speeds. The electric motor engages primarily to reduce engine strain during acceleration, which significantly boosts fuel efficiency in stop-and-go driving conditions. It does not engage during normal highway driving, so it provides less benefit at higher speeds.
The gearing of the five-speed insight is also engineered to maximise fuel efficiency at all speeds, so travelling at freeway speeds in the highest gear will still yield desirable results. The CVT, however, sacrifices some fuel efficiency to produce fewer and cleaner emissions. With its emphasis on emissions, the CVT loses power and this is most notable at higher speeds.