This might be a stupid question, but what's the difference between a 2003 and 2003.5 G35 sedan? I have an 03 sedan with all the options pretty much, Nav, SP, PP, Spoiler, but how can I tell if what 03 model it is? I bought it used from an Infiniti dealer a few months ago, but never asked them to clarify this.

 

Look at the trunk. Early 2003 had the external trunk latch. 2003.5 they removed the latch. An improvement in IMHO.
Other that that, I don't know of any other differences.

 

That square bracket thing on the '03 trunk had a button release on the trunk lid. The '03.5 doesn't, but instead has an interior trunk-release switch that the '03 doesn't. The '03.5 has a 12v power outlet on the passenger side of the console, embroidered logos on the front seats, the cargo net is full-width instead of about 2/3rds width. Some defects in the '03 like the noisy alternator are fixed in the '03.5. A couple of other minor cosmetic changes (like chrome bezels on the radio panel, I think). If memory serves, I believe the HID lights also became a standard part of the leather sedan, instead of an option.

 

Also has infiniti stitching in seatbacks, plus I believe it the auto got a transmission program update.

g4ian

 

The coupe-style transmission program came along in '04.