Updated at: 20-07-2022 - By: Lucas

In-line four-cylinder engines are the most common in today’s automobiles. However, there are many more powerful engines, with six, eight, ten, or even twelve pistons. Aside from the four-cylinder engines, the vast majority of automobiles have six-cylinder engines. However, there are a variety of them. Which six-cylinder engine is the most fuel efficient?

Advantages of the inline 6 engine

1. Cheap and easier to manufacture

A six-piston engine block is easier and less expensive to make because of its design. If the casting mold is composed of steel or aluminum, the process of filling it with material is simple and straightforward. However, the lower cost of production is not always reflected in the ultimate cost of an automobile.

2. Higher torque at higher engine speed

The six-cylinder in-line engine produces more torque at a higher RPM than a V6 because the pistons are aligned and the engine is longer. Over time, numerous off-road vehicles have been outfitted with six-cylinder inline engines because of this benefit. The necessity for torque at any speed has led to the installation of this type of engine in many trucks and large vehicles.

3. Simple design

An engine with only six cylinders has only one cylinder head, half the number of cam axles, a single gasket, and a simpler path for the coolant to flow through. There are numerous advantages to a simpler design, such as less complexity. Improved lubrication, shorter belt, etc.

4. Balanced motor by construction

An inline 6 engine is more balanced than a V6 because of its architecture. The ignition order maintains the proper balance of the pistons, which only move in one direction: up and down. A well-adjusted engine, on the other hand, produces less noise and vibration than a V6.

Disadvantages of an inline 6 engine

Comparison V6 Vs Inline 6 Engine-2

1. Useless for front-wheel-drive cars

The engine’s layout, which features six pistons aligned inline, precludes the use of efficient front-wheel drive automobiles. There is just no room for it to be mounted transversely, near to the gearbox. Only BMW automobiles, which have all-wheel drive and are equipped with such engines, use a driveshaft that connects the transmission to the front axle. It was found that Volvo’s inline 6 and FWD automobiles were inefficient.

2. They have a lower speed than a V6 engine

Having a longer crankshaft that spins through seven bearings, compared to four for a V6, it has a higher level of friction by design. Even though the engine is relatively large, it takes a long time for air to reach its final pistons due to the difficulty in getting it there.

3. Higher fuel consumption

The consumption of engines with six pistons in line is higher than that of a V6 because of the high internal friction of the parts and the difficulty of the intake. Modern engines, on the other hand, have found a solution to this issue through the use of planned fuel injections and overfilling.

4. More difficult cooling

Because of the engine’s length, the cooling pump sometimes delivers less water to the final two pistons, causing them to overheat. Modern inline 6 engines now have induced cooling at both ends of the engine so that coolant reaches each piston and the engine’s internal temperature is evenly distributed throughout the engine.

5. Lower torque at maximum speed

Making a perfect engine is a difficult task. When an inline 6 engine has a wide torque range at low speeds, it loses this advantage at high speeds because it loses power and torque, even though they start early and are present most of the time.

Advantages of the V6 engine

Comparison V6 Vs Inline 6 Engine-1

1. Suitable for any kind of thrust

Due to the V6’s small size, it is suitable for vehicles with front-wheel drive, all-wheel drive, or rear-wheel drive. Many vehicles, including as the Hyundai Coupe, Honda Legend, and Toyota Camry, are available with V6 engines and front-wheel drive. A V6 engine can be fitted in the front, back, or center of the vehicle whereas a 6-cylinder inline engine is installed in the front.

2. Higher speeds than the inline 6 engines

Engine blocks are smaller and cylinder heads are shorter in length in a V6 engine. Because of the shorter crankshaft and shorter piston stroke, these engines can run at faster speeds than inline six engines. For this reason, trucks choose inline sixes for torque, whilst racing cars prefer V6s for horsepower.

3. Friction is much smaller than an inline 6 engine

There are four bearings on a V6 engine crankshaft instead of seven on a six-cylinder engine with six pistons arranged in a straight line. The movement of the pistons in the engine block is significantly reduced. This means that internal friction is minimized, resulting in increased speed and acceleration, lower consumption, and a lower operating temperature, all of which contribute to lower fuel consumption.

4. Extremely compact engine

In many cases, a V6 engine is more compact than a 4-cylinder engine. Most manufacturers favor this engine because its design is nearly identical to that of a three-piston engine, but it is broader at the top, making it more adaptable and allowing it to be positioned either longitudinally or transversely under the hood.

5. Easier to over-fill

All six pistons are equally well served by the intake’s small design. Numerous automakers have opted to supercharge V6 engines in order to increase their output, as is the case with the Nissan GT R. Engines with six pistons in line can also be supercharged, although the process is more expensive and less economical.

6. Low weight compared to an inline 6 engine

Despite having two cylinder heads, a V6 engine is smaller and lighter than an inline 6. As a result, the automobile will use less gasoline overall and perform better in sports mode. It is also possible for manufacturers to move around an improved V6 engine to better balance a compact automobile because of its small size.

7. Easy cooling

The water pump’s compact design makes it considerably easier to handle and distributes the coolant evenly around the engine’s six cylinders. Because the antifreeze route is shortened, cooling occurs more efficiently, ensuring that the temperature is uniform throughout the touring range and in all pistons. As a result, an inline 6 is more likely to overheat, particularly in hot weather.

Disadvantages of a V6 engine

1. Complex and expensive design

In comparison to an inline 6, a V6 engine has two cylinder heads, two injector ramps, and twice as many camshafts. Because the strain on these parts is half compared to an inline motor, this does not necessarily mean that it has a poor level of reliability. In addition, a V6 engine’s production costs are higher.

2. Noisier engine

V6s are more imbalanced and noisier than inline 6s because of their design. There are stresses on four axes, up, down, left and right from the four pistons. As a result, the internal components will experience an increase in vibration, which over time may cause damage.

3. Low torque and low power at low speeds

The V6 engine, in comparison to an inline 6, is built for higher speeds and quicker accelerations. At low speeds, its torque and power aren’t boosted. Pushing the gas pedal all the way down is the only way to get the most out of a V6 stock. As a result, we see an increase in overall consumption.


It’s possible that BMW’s monopoly on automobiles with inline six engines (all others have V6s) isn’t by accident. In contrast to Mercedes and Nissan, which abandoned the inline 6 in favor of V6s, the Bavarian manufacturer just wants to maintain history.

However, if we consider the pros and disadvantages in detail, it appears that the inline engine holds a slight advantage due to its higher torque and power, simpler design, lower cost, better balance, quieter operation, and higher reliability. When it comes to a V6, this means that it’s smaller, more flexible, lighter, and more efficient. As a result, each engine has its advantages and disadvantages because no one engine is perfect.

There’s no doubt about it.

There is nothing wrong with any of the engines on the market. Due to BMW’s financial resources, it is the only producer of inline 6 engines that can deliver extremely high-performance inline engines, which is why the cars are so expensive. Competitors, on the other hand, have opted for larger, more powerful V6 or V8 engines, which are then turbocharged twice.

As a result of the mad dash to save costs, inline six engines have all but vanished from modern automobiles. BMW could lose the appeal of this layout if they go down that path and succumb to the economics.