Highway Loop: Black Vista Highway is one of the maps in Twisted Metal: Black.
Near the bridge there are large sphereical objects that you can hit with a gas can, one of them will then break of its fundaments and start rolling towards the nearby tunnel, where it will explode and create a hole in the wall revealing a secret chamber containing a hidden level and a few power ups. But, if any car touches it, the sphere explodes, and you won't be able to open the secret area. So it best to kill 6 or 7 of the 8 opponents before trying to get the secret level.
There are 2 spots where you can fall into the water and instantly lose a life. One of them is near the spherical gas tanks, and the other is at the opposite side of the map, on the large bridge.
This level is clearly harder than Downtown, because the latter is more open and there are slightly less opponents.