What is the correct matching of speed and RPM?

[LaClaire]

Speed and RPM correct matching is: at 120 km/h the optimal RPM is 3400 rpm. Top gear RPM introduction: Under normal driving conditions, the engine RPM in top gear is as follows: when the speed reaches 100 km/h, the RPM is generally 2800 rpm; when the speed reaches 110 km/h, the RPM is generally 3200 rpm. The relationship between engine RPM and vehicle speed: The conversion relationship between engine RPM and vehicle speed is: vehicle speed = engine RPM × current transmission ratio × wheel circumference. From this, it can be seen that engine RPM and vehicle speed do not have a one-to-one correspondence, but also depend on the current gear, that is, the transmission ratio. At the same speed, the RPM will be smaller. When driving, if the vehicle's speed remains the same but the RPM becomes lower or higher, this is related to the vehicle's displacement, and another factor is the transmission gear.