my understanding is that the 2003 (265 hp) cars can run on 87 octane fuel, (91 octane recommended for optimum performance). The newer 285 hp rated engine configuration requires high grade fuel...?

 

All cars can run on 87 octane. The knock sensor takes care of the lower octane to avoid pinging. The difference is that in some cars the manufacturers recommends 87 and some like Infiniti recommend 91. I had a 96 Maxima, which Nissan also recommended premium fuel. Over the course of my ownership (7 years) I did many experiments and running on 87 would always give me worse MPG. I've only had my G for 1 months, but I wouldn't be surprised if the same trend happens.

 

Does this mean read the fine manual? It kills me how many people buy cars and drive them without actually opening the fine manual.

 

My 05 6MT says "Premium unleaded fuel only" on the gas door.

 

DITTO

 

I live in Canada and put the regular in, 87 octane. No problems so far...and still decent performance.