There is a glitch in the program to control the automatic transmission, and therefore the hydraulic pressure of the transmission input clutch on certain vehicles is low. When such a vehicle is driven in 5th gear at high speed, the clutch may slip causing the engine revs to increase. If the vehicle continues to be driven in this condition, it may happen that vehicle body vibration is generated and the clutch slips in a lower gear, making it difficult to accelerate in accordance with an accelerator operation, and at worst driving at medium or high speed could become impossible.