i have an 06 auto sedan and it said premium recommended. so is it only the sedan sport package is premium required?

 

any VQ will take 91 or better. the options package does not matter. engine stays the same.

 

Not true.

For '05-06...

5AT (sedan and coupe) = 282 hp and 269 lb·ft of torque, 91+ octane recommended
6MT (sedan and coupe) = 298 hp and 258 lb·ft of torque, 91+ octane required

 

^Why would the transmission make any difference to what gas is required/recommended?

 

The engine was tuned differently depending on which tranny it was mated to.

Question it all you want, but I'm stating fact straight from Infiniti here.

 

my friend's 06 5at coupe is premium required. That's what im confused about.

 

Tell him to RTFM, and he should find it says "recommended" not "required."

 

I'm not doubting that it may be listed like that. What I'm questioning is if it makes any sense. Each engine is going to have the same compression...

 

...but may have different timing and/or different AF mapping in the ECU.

 

It has more to do with the extended redline of the Revup engines.

 

How would you explain the lower peak torque on the 6MT variant then?

 

Copied and pasted directly from the 2005 manual (pdf) -- *no* distinction between AT and 6MT:

FUEL RECOMMENDATION:
Sedan models
Use unleaded regular gasoline with an octane rating of at least 87 AKI (Anti-Knock Index) number (Research octane number 91).

For improved vehicle performance, INFINITI recommends the use of unleaded premium gasoline with an octane rating of at least 91 AKI number (Research octane number 96).

Coupe models
Use unleaded premium gasoline with an octane rating of at least 91 AKI (Anti-Knock Index) number (Research octane number 96).

 

Copied from the 2006 manual (pdf):

 

None of this makes any sense to me. Am I the only one?

 

marketing bullsh!t. Any year coupe or sedan including G37s will not blow their engine on 87 octane. They will be slow as **** but nothing will happen.