DistanceGP2Y0A21YK Dist01; //defines Dist01 as the sharp GP2Y0A21YK
Really? I'd never have guessed. 
Dist01.begin(A0); //tells program "Dist01" will be used by the serial monitor
That statement does NOT do what the comment says.
You should look at arrays for similar things.
/*
Although below, it says "getDistanceCentimeter", it really converts the data into Inches---make a very big note for this!!
*/
Or get smart and rename the function.
if ((Prox01 <= 10) || (Prox02 <= 10))
Steering.write(125);
else if ((Prox04 <= 10) || (Prox05 <= 10))
Steering.write(65);
else if ((Prox01 <= 15) || (Prox02 <= 15))
Steering.write(115);
This collection of if tests is way too complicated. There has to be a simpler way.
How are the sensors oriented?