The first sentence is easy: "I walk past her"
The second sentence is more problematic, because in English a motorist does not ride, they drive. In UK English, you would only use 'motorist' when you are talking about car drivers, and even then you would be more likely to use 'driver'.
So, was it a motorist or a motorcycle rider?
Here's 2 possible solutions:
"The motorcyclist rode towards me"
"The car drove towards me"
Finally, you need to decide whether the vehicle is actually coming towards you, or if it is passing close by you.