If you believe the line then it's 50/50 whether STL covers 7.5.
If you believe the ML which is roughly -300 (+280/-320). -300 means STL should win SU 3/4 times -- 75% of the time.
So put this on a graph. A 50% of STL covering 7.5 and a 25%chance of Car winning SU leaves 25% for evrything else contained in your middle.
Of course you also own Car by 1, but that's probably not even a 2% chance so that's why I say slightly better than 25%.
Of course you should adjust accordingly if you think the lines are not accurate.