In which gear does the car consume the least fuel? [management]

Car manufacturers encourage us to use high gear ratios with shift indicators and engine performance. Meanwhile, not every driver is convinced to use them. Many people think that a high gear puts so much stress on an engine that it burns fuel in a lower gear. Let's check.

If we break down fuel consumption into the most important components that directly affect it, and those that are affected by the driver, then these are:

• Engine RPM (selected gear and speed)
• Engine load (pressure on the gas pedal)

к engine speed depends on the selected gear while moving at a certain speed engine load is directly dependent on the position of the accelerator pedal. Can the car drive uphill with a light load and downhill with a heavy load? Of course. It all depends on how the driver presses on the gas. On the other hand, there is little that can be changed if he is going to maintain speed, so the steeper the road, the heavier the car, the stronger the wind or the higher the speed, the greater the load. However, he can still select a gear and thereby relieve the engine. 

Some people like it when the engine runs in the middle range and stays in a lower gear longer, others prefer a higher gear and lower rpm. If the speed is lower during acceleration, then, contrary to appearances, the load on the engine is greater, and the accelerator pedal must be pressed deeper. The trick is to keep these two parameters at such a level that the car runs as efficiently as possible. This is nothing more than a search for a golden mean between load and engine speed, because the higher they are, the higher the fuel consumption.

Test results: downshift means more fuel consumption

The results of the test carried out by the editors of autorun.pl, which consists in overcoming a certain distance with three different speeds, are unambiguous - the higher the speed, i.e. the lower the gear, the higher the fuel consumption. The differences are so great that they can be considered significant for a longer mileage.

The test Suzuki Baleno, powered by a 1,2-litre naturally aspirated DualJet petrol engine, was driven in three tests at speeds typical of Poland on national roads: 50, 70 and 90 km/h. Fuel consumption was checked in 3rd, 4th and 5th gear, with the exception of 3rd gear and speeds of 70 and 90 km / h, because such a ride would be completely pointless. Here are the results of individual tests:

Speed ​​50 km/h:

• 3rd gear (2200 rpm) - fuel consumption 3,9 l / 100 km
• 4rd gear (1700 rpm) - fuel consumption 3,2 l / 100 km
• 5rd gear (1300 rpm) - fuel consumption 2,8 l / 100 km

Speed ​​70 km/h:

• 4rd gear (2300 rpm) - fuel consumption 3,9 l / 100 km
• 5rd gear (1900 rpm) - fuel consumption 3,6 l / 100 km

Speed ​​90 km/h:

• 4rd gear (3000 rpm) - fuel consumption 4,6 l / 100 km
• 5rd gear (2400 rpm) - fuel consumption 4,2 l / 100 km

The conclusion can be drawn as follows: while the differences in fuel consumption between 4th and 5th gear at a typical driving speed (70-90 km / h) are small, amounting to 8-9%, using higher gears at city speeds (50 km/h) brings significant savings, from a dozen to almost 30 percent., depending on habits. Many drivers still drive around the city in low gears and downshift when passing through the highway, wanting to always have good engine dynamics, not realizing how much this affects fuel consumption.

There are exceptions to the rules

Recent cars have a multi-speed automatic transmission that often shifts to 9th gear on the highway. Unfortunately extremely low gear ratios do not work in all conditions. At a speed of 140 km / h, they sometimes turn on at all or very rarely, and at a much higher speed of 160-180 km / h they no longer want to turn on, because the load is excessive. As a result, when manually turned on, they increase fuel consumption.

There are situations, for example, when driving in the mountains, when in heavier cars with automatic transmission it is worth using a lower range of gears, because modern automatics usually try to keep a low speed, even at the cost of excessive load on the engine. Unfortunately, this does not lead to a reduction in fuel consumption. It is not uncommon in difficult conditions that vehicles with transmissions with a large number of gears burn less, for example in sports mode.