To be more fuel-efficient at high speeds, you need to switch frequently between d and m gears. Using only one gear does not achieve a good fuel saving effect. The fuel saving problem of M and D gears is actually very troublesome. M gear, the car can be adjusted to 2 gear, but the 3rd gear speed as long as it reaches 2200-2400 rpm can be hung, 4 gears 1800-2000, 5, 6 gears 1600-1800; D gear, from 2-6 gears are 1800-2000. Therefore, if you want to save fuel, you need to switch between D and M often.
D gear: Automatic forward gear in economy mode, the transmission ECU will automatically select the active upshift according to the speed and speed of the car to maintain the balance of power and comfort. M gear: Switch to manual mode, which is only the function of the manual transmission; simulate manual control of shifting (at this time the automatic transmission does not automatically shift gears), and need to manually push the speed shift "M+/M-" according to the speed and engine.
M-stop can theoretically be used for a long time. As far as the gearbox itself is concerned, it is simply the difference between the automatic and manual control of the shift program. However, because the gear is after the M gear, the engine speed is high and the torque is large, which is suitable for climbing or accelerating overtaking. As a result, fuel consumption will increase a lot. If the gear is often shifted in the limit speed or state, relatively speaking, due to the difference in speed and load, the wear will be more or less aggravated, and the maintenance cycle of the lubricating oil will be shortened.