In the continued battle to maximize fuel mileage and minimize exhaust emissions, auto makers around the world are struggling with a decision: the choice between continuously variable transmissions or those with dual clutches.
Both offer the fuel savings of a manual gearbox with the convenience of an automatic transmission. Both work especially well with small, light vehicles powered by low-displacement engines. One is popular in Europe and the other in Japan.
North Americans continue to heavily favour the pure automatic transmission. More than 90 per cent of all vehicles sold in Canada and the United States are so equipped. Outside of the province of Quebec, where manual transmissions continue to find favour by more than 20 per cent of consumers, automatics are the clear winner.
The big decisions related to our market are the number of gears in that automatic transmission. The current range is four to seven with the former rapidly becoming very outdated.
We continue to buck world trends by buying large, heavy vehicles requiring large-displacement engines mated to automatic transmissions. But soaring oil prices and the strong likelihood of sustained higher gas prices have the folks in the planning department of most auto manufacturers looking very closely at smaller, more fuel-efficient vehicles -- and drive trains.
If the SUV-pickup train falls off the track and consumers start looking for less costly choices, the company with the best alternative will win.
Thankfully, today's auto industry is a truly global business and virtually all the major players have worldwide affiliates. This will allow them to move quickly to bring appropriate vehicles and power trains to our market when demand warrants.
It also means we should watch this whole transmission issue with more interest since it is not a case of Europe versus Japan, but one of what we will be driving in the future.
An internal combustion engine works most efficiently at a steady speed. Engineers can determine the amount of fuel delivered, its flow into the combustion chamber and the timing of the ignition to maximize the combustion and minimize the leftovers that go out the tail pipe as emissions.
The biggest problem they face is when an engine is required to speed up and slow down -- constantly changing the amount of fuel delivered and making the process less efficient.
With only a few gears in a transmission, the range of engine speed is much wider. For example, a four-speed might result in a difference of 1,500 rpm in engine speed between gears while a six-speed might result in half that. Obviously it will be easier to calibrate an engine operating over a more narrow range.
That explains the need for more gears, but what about the issue of continuously variable transmission (CVT) versus dual clutch?
Both are battling for supremacy in smaller, lighter vehicles in markets where both purchase prices and fuel prices are much higher than in North America. While consumers in those markets appreciate the more fuel-efficient manual gearbox and the lower initial cost, they are moving steadily toward some form of automated shifting and that's where the interest in the CVT and dual-clutch designs grows.
A CVT is essentially a fully automatic transmission that uses belts and pulleys to vary the gear ratio based on engine speed. A dual-clutch transmission is a manual transmission that can be operated in automatic mode.
The CVT allows engine speed to be kept almost constant while vehicle speed varies. But it is more expensive to produce than a dual clutch and requires different packaging. A dual clutch unit is less expensive and fits more easily but requires an engine to operate over a wider range.
Europe's largest vehicle manufacturer, Volkswagen, is pushing its DSG (Direct Shift Gearbox) dual-clutch setup, while several Japanese manufacturers, including Honda and Nissan, favour CVTs.
