Octane is a spark retardant to prevent preignition in high compression engines.
My guess on the smell is that the enigne is running rich on the 87 octane due to the computer having to alter its settings for proper timing air/fuel ratio, etc.
If an engine says use 87 octane, then it doesn't generally do any good to run 89 or 93 in it; unless it's an old engine with a distributor and someone manually advanced the timing. But on these engines with a computer contolling the system, it doesn't help, just makes you lower on cash.
Try running 5 to 7 full tanks of 87 in the car and see if the computer doesn't compensate. If the fuel smell is still there, then go back to the 89 grade.
Good luck.
