I'm offended by my girlfriends opinion of a car
Why are you offended at your girlfriend's opinion?
She critcized the car because of lack of space
I understand you have your own opinions, but you can't expect everyone -- including your girlfriend -- to agree with you all the time. Maybe she's pregnant and thinking about the car in terms of where the baby will be sitting!
It's stupid not to like something because there is not much space.
Let her express her opinions just as how you express yours. Everyone want to give their input on things, maybe she is trying to persuade you to buy another type of car. Don't let it irk you so much.