Why Going for More and More Gears in Automatic Transmissions

Nowadays, you have to put a great deal of effort to find a car that offers fewer than 5 gears, and even then it’s mainly on an obsolete base model. In the 80s carmakers started applying 3-speed automatic transmissions. During the 90s and early 00s the 4-speed transmission dominated as a standard solution for automatics and a 5-speed was a top pick for the manual gearbox. The first seven-speed gearbox popped up in 2003 thanks to Mercedes-Benz, but seven and eight-speed transmissions were only offered within the luxury car world for quite some time.

But currently it seems that the whole automobile industry became obsessed with more and more sophisticated transmission solutions. Today it’s no surprise that the 2018 Honda Odyssey is tested with the 9-speed automatic transmission, the 2018 Acura RLX has a 10-speed automatic transmission with Sequential Sport-Shift paddle shifters and Grade Logic Control, and that Ford considered a 13-speed automatic transmission for the Ranger Raptor. This trend to more gears should have some logical explanation. Let’s see what’s really going on here.

Check out the test drive of Ford F-150 equipped with the 10-speed automatic transmission

So why more gears? Each carmaker pursues different goals while applying automatic transmissions in new cars. The list of potential advantages of such solution includes smoother shifts, enhanced fuel efficiency, and improved performance characteristics. In addition, a higher gear count also may look more attractive from a marketing standpoint, simply by giving potential buyers the impression that the vehicle is stuffed with high-tech solutions.

But some carmakers try to avoid new and higher ratios to ensure the product durability. In addition to reliability concerns, some experts assume that the design complexity and higher production cost of automatic gearboxes with more gears may be an unprofitable investment. If carmakers produce transmissions with more gears just to keep up with competitors in complexity of their solutions, then this investment may turn out to be not so lucrative on a long-term horizon. Therefore, experts believe that automatic transmissions with more gears may be a good idea, but introduction of such sophisticated transmissions should be a well-considered decision instead of a simple desire to outperform competitors in the technology complexity.

More insights into the issue of more gears

So let’s review main arguments of supporters and opponents of automatic transmissions with more gears in more detail.

Arguments in favor of more gears in automatic transmissions

Advocates of applying more gears claim that there are closely reasoned arguments confirming their beliefs. So let’s gain insight into opinions in favour of more gears.

1) Better efficiency

Many specialists say that it is easy to understand the benefits of applying more gears in automatic transmissions. There are some common principles when talking about transmission efficiency. For example, the most suitable method for driving at a certain speed is to apply the lowest possible RPM (revolutions per minute). The low-level RPM ensures less drag losses and fewer combustion strokes per minute, which results in enhanced fuel efficiency. When it comes to acceleration, usage of the highest available gear may be not the best option. In high gears, the vehicle operates very intensively to surpass a gearing shortcoming (high gears imply lower wheel torque) in the process of acceleration. Availability of a huge number of gears ensures higher ratio spread between them, meaning that the engine has more options for effective operation. The spreading of the ratios helps to put the engine in the most effective area of operation.

Learn more about famous 9HP

2) Improved acceleration

We will take the Aston Martin Vanquish to see how the application of the gearbox with more gears affects the car speeding-up. The off-the-line acceleration to 97 km/h took 3.6 seconds (0,5 second faster) when this car was equipped with the 8-speed ZF gearbox instead of the 6-speed ZF gearbox and the same engine. How so? Now let’s suppose that the 6-speed gearbox reaches the maximum speed of 129 km/h at the second gear. The 8-speed gearbox, in turn, provides shorter gearing because of a wider range of ratios to choose from, therefore its maximum speed at the 2-nd gear is 105 km/h. Because the 8-speed gearbox provides more aggressive ratios, the torque will be higher before reaching the speed of 105 km/h. Therefore, the 1-st gear is shorter to faster speed up the car from a standstill while the top gears can be taller for better fuel efficiency.

Review and Test Drive of Aston Martin Vanquish

3) Some drivers are not happy with CVT performance

Many engineers think that CVT is an ideal transmission solution for modern cars and there is a deal of truth in it. Today the CVT solution practically offers a limitless range of ratios, theoretically reducing the value of fixed-gear transmissions. Moreover, CVTs are distinguished by more smooth and efficient operation, better speeding-up, and even faster shifting when predetermined ratios are selected.

But, on the other side, despite all CVT advantages, this technology neglects several significant factors related to the driving experience, such as responsiveness. Some drivers feel odd while driving cars equipped with CVTs, as the engine and gearbox do not behave the way most drivers are used to. In addition, CVTs are mainly good for cars with small-displacement engines, but engines with higher capacity that provide more power and torque cannot be handled by the CVT, therefore in such cases the automatic or DSG transmissions look more preferable.

Informative videos about CVT

4) Why not DSG transmission?

Giving credit to advantages of DSG transmissions, like fuel economy and rapid gear shifting, in comparison with automatic transmissions, automatic transmission admirers still have reasonable doubts about the DSG technology. The warranty of a DSG transmission does not cover many problems that emerge in the process of transmission operation. Owners of cars with DSG transmissions constantly have to deal with issues related to the Mechatronic unit. There are many problems when it comes to the transmission repair: few competent DSG transmission specialist, high-priced repair services, problems with spare parts supply for DSG transmissions. Therefore, many carmakers think that DSG technology is still not good enough and prefer to design new transmissions on the basis of well-tried automatics.

Informative videos about DSG

Arguments against more gears in automatic transmissions

Now we will consider arguments of people who are strongly convinced that automatic transmissions do not require more than 7 gears.

1) More complex automatic transmissions add more costs

It should come as no surprise that the more gears are included in the transmission, the more structural components are implemented in the transmission design. Moreover, the assembly process of automatic transmissions with multiple gears is more time-consuming and it certainly increases the cost of production. It is natural that, in terms of design, 9-speed transmissions are more complicated than 7-speed transmissions. This means that chances of failure in 9-speed transmissions are much higher than in 5-speed transmissions. Thus, when buying a car with a 9-speed automatic transmission customers not only pay the extra money, but they also get the car with a higher probability of the transmission failure. The cost of repair services of automatic transmissions with 8-10 gears will be significantly higher when comparing with the repair cost of 5-6 speed automatic transmissions.

2) More gears result in more weight of transmission

Usually car manufacturers try to reduce the weight of their brand-new cars, but doing it at the expense of transmissions with a large number of gears turns out to be unfeasible. No matter what case is used for positioning of the transmission internal components, 8-12 speed transmissions will weigh more than, for example, 6-speed transmissions. And it is known that the additional weight is the enemy of car performance characteristics. All car manufacturers know that to make a car more efficient you have to reduce its weight; therefore usage of 8-12 speeds automatic transmissions looks even more unreasonable. But if car makers decide to follow a modern trend “The more gears, the better”, they still will have to reduce the total car weight at the expense of other important components in order to stay competitive on the market. It also should be mentioned that usage of heavier transmissions may lead to overloading of the car’s fore-body. This is especially true for front-wheel drive vehicles. The heavier the transmission, the more unbalanced is the weight distribution between front and rear axles. Thus, the application of the transmission with a large number of gears, which weighs more than an analog with fewer gears, is not the best engineering solution.

3) The more gears in transmission, the more often gears are shifted

Almost all modern automatic transmissions with multiple gears usually adapt to the driving style of the car owner. Thus, with the help of this feature the transmission operates more efficiently, but it doesn’t mean fewer gear shifting operations. The fact is that any automatic transmission constantly shifts gears in the process of movement at different speeds. It is reasonable to assume that the more gears an automatic transmission has, the more often it shifts these gears. For example, even standard 4-5 speed automatic transmissions annoy drivers with constant shifting. Imagine what will happen when driving a car with a 10-speed transmission. You don’t have to be an expert to understand that frequent gear shifting damages the transmission internal components. The more intensively the transmission operates, the faster its components wear out. It is worth thinking about the transmission durability, when, for example, the car with a 9-speed transmission has to shift gears 8-9 times to accelerate to particular speed from a standstill.

4) “More gears contribute to the fuel economy” is just a marketing ploy

Most automakers claim that implementation of more gears significantly improves the fuel economy, while advertising their brand-new cars with 9 or 10-speed transmissions. But it seems to be a disputable statement.

In fact, the maximum fuel economy of cars with 9-speed automatic transmissions amounts to 0,25-0,3 liter per 100 kilometers when comparing to 7 or 8-speed transmissions. Even if we take older automatic transmissions with 5 or 6 gears, the maximum fuel economy of the car with the 9-speed transmission will be about 0,5-0,6 liter per 100 kilometers. At first thought, it may seem as a sufficient improvement in fuel economy. But in practice, this slight improvement is eliminated by other factors. For example, driving style, weather conditions, and even car tires may have more significant impact on the fuel consumption parameter than the most expensive 9 or 10-speed automatic transmission.

5) Overestimated performance improvement

It is no use arguing that, for example, 6 or 7 speed automatic transmissions improve the acceleration parameter of the car when comparing with older 4 or 5-speed automatic transmissions. But it doesn’t mean that constant adding of gears to automatic transmissions will improve performance characteristics all the time. To make a point, let’s consider a 21-speed mountain bike with many speeds. Bike riders mainly use a specific set of gears (1-7 and 14-21) while others stay mostly unengaged. The same is applied when dealing with cars - 5 reasonably close ratios with 1 or maybe 2 tall gears for highway cruising will have the same impact on acceleration characteristics as transmissions with a nearly doubled amount of the gears. Therefore, 9-speed automatic transmissions generally use the same shafts and gears as 5 or 6-speed transmissions; consequently, there should be no significant difference between acceleration parameters.

Compare acceleration parameters of 6 and 9-speed automatic transmissions

What is next?

What is the future of automobile transmissions? Experts continue arguing about pros and cons of different transmission types, but most of them concur that there is no ideal transmission for all conditions. While debating about pros and cons of automatic transmissions, CVTs, and DSGs, we should not give up on manual transmissions. Despite the fact that manual transmissions lost prestige in many countries, they still have some significant advantages: lower production cost, reliability, experience of being in charge of gear shifting. Moreover, manufacturers still develop and produce new manual transmissions with improved parameters and are ready to compete for their segment of the driving public.

Continuous tightening of environmental standards forces manufacturers to improve not only engines, but also transmissions. Electrified transmissions will certainly gain more popularity as major automakers such as Mercedes-Benz and Toyota take on obligations to make their products more environment-oriented. However, a car with a hybrid transmission is quite complicated and expensive. Apparently, the repair of such transmission will also be high-priced.

Manufacturers of automatic transmissions, CVTs, and DSGs will stay strong in the pursuit of their goals and will continue developing more and more sophisticated transmission solutions. All in all, it seems very unlikely that any of above-mentioned transmission types will become extinct in the near future.

To sum it up, the question about more gears in automatic transmissions is a tricky issue and gives a mixed impression. On the one hand, more gears keep everyone happy, and it doesn’t hurt that you get a smoother feel when accelerating and passing on the highway. On the other hand, all the fuss about more gears in automatic transmissions seems like a marketing ploy in an effort to draw more customers with more sophisticated (but not necessarily more reliable and cost-efficient) technologies.