My sister said that my car pollutes because it is an SUV BUT?

My sister said that my car pollutes because it is an SUV BUT?
she too drives a car and thinks that she is high on a horse because she says im causing more damage since i drive a car that takes up more fuel

BUT i know she is not correct, help me maintain my idea so she can not be so stubborn and think she helping the environment-as she thinks she is, since she drives a pontiac and not an SUV