I took the car to an old gymnasium this morning. I had adjusted the "frontfree" distance from four feet to five feet.
That's the proximity response from the front sonars which triggers the code to turn sharply left.
I left the potentiometer at the speed that was too fast for my garage. In the gym it negotiated the corners fine, but could not hug the wall.

I may need to recalibrate the steering, but more likely I need to restructure the wall hugging code.

Here's a link to the code I am presently running. The only difference between the toy car code and the model car code is the servo and DC motor driving commands. For the model code I use the HPWM PicBasic command. For the toy level I command certain pins to be HIGH or LOW.

http://www.employees.org/~kjones/HPI2_left_SyRen02.htm

Ken