Lord knows, I'm full of snappy comebacks. But when someone is asking you something like that & they give you the benefit of the doubt that it's not just another 318, but the higher performance motor, they're just curious about you car & looking to engage you in conversation about it because they like it. Take it as a compliment & then tell them what it really is & some more about it. I wouldn't bite their head off over it. I'm sure you have asked just like the rest of us, someone at sometime, what they have in their car & guessed wrong. It just happens.
