This is the same as Speed Kills, but you have to ram through at least four opponent vehicles in one ramming boost. This is best done in Exhibition on a small track where you can set the amount of opponents to the maximum to give you more of a chance of ramming four vehicles in one boost. Wait for them to gather up at one end of the track and go for it.
Ibn a Banger Race, get to Ramming Speed (by crashing into the other cars and picking up boost) and fall back to last place on a straightaway, but stay close to the other cars. Then use the speed boost to ram through four cars from behind.