How to Increase vehicle speed during gameplay ? and other issues

I want to make a racing game. Finally I have managed to import my own vehicles and i can control them using keyboard buttons too. There are some questions i want to ask about the wheel vehicles.

  1. How can i increase the speed vehicle to its maximum value ? I have already tried increasing the rpm number, changing the torque curve but it didn’t give me the speed which i want. Like i want the blazing speed as in Burnout or NoS ? how can i acheive the same output ? do i have to use add linear physics or impulse nodes?

  2. How can i change the speed of my car during gameplay? Like there is no option of setting the rpm number in blueprint scripting.

Thanks in advance and Love from Pakistan <3