Another brand stepping into mystery flacours is Mentos. I have only seen this in one service station so I'm not sure where you might find them.
The flavour was definitely from the citrus group (which I love), I'm going to say lemon (although the third listed ingredient is grapefruit juice but if it is grapefruit it is very mild). Being a fan of citrus, I demolished the packet in no time. Could have been more sour, but you can pretty much add that comment to any candy I review.
Rating: Not exactly an exciting mystery flavour, but yummy none the less, 7/10