Final answer:
We cannot determine the miles per gallon difference between Riley's and Evan's cars based on the given options.
Step-by-step explanation:
In order to find out how many miles per gallon more or less Riley's car gets compared to Evan's car, we need to find the actual miles per gallon for both cars. Unfortunately, the information provided does not give us the specific fuel efficiency for Riley's and Evan's cars. Therefore, we cannot determine the answer based on the given options A, B, C, or D.