Hey, I was looking this up today... why is a 2013 G37 coupe's curb weight more than a 2007 G35 sedan?

g35 sedan = about 3550 lbs
g35 coupe = about 3300 lbs

g37 coupe = about 3770 lbs.

I compared a couple other examples and found coupe models to be 300-600 lbs lighter... as one might expect.

Is it... the 37 engine?

 

Not sure about those weights you posted, but coupes are typically heavier than the sedans they are derived from. A coupe does not have a B pillar, which sedans do. The B pillar adds considerable rigidity to the structure of the vehicle. For a coupe to gain back the rigidity lost without a B pillar, extra reinforcement of the chassis is added. This reinforcement adds mass, often adding up to a greater weight than losing two doors.

The engine, gearboxes, wheelbase, etc are the same between coupe and sedan.

The G37 coupes are heavier than the sedans if you compare like trims, but the difference is not much. The G35 coupe was more of a porker compared to the G35 sedan.

 

*scratches chin*

 

Your numbers look a little off. Check out this link here:
2009 Infiniti G37 vs. 2009 Infiniti G37 vs. 2009 Infiniti G37 vs. 2009 Infiniti G37

If you scroll down and compare for the four trims on that link, here are the weight for each different trim:

G37 sedan journey: 3590 lbs.
G37 coupe base: 3633 lbs.
G37 coupe journey: 3642 lbs.
G37 coupe sport: 3662 lbs.

Sedans come with 17" wheels. Less rotational weight should give better acceleration times in 1/4 miles than the coupes.

Check out this Base 7AT G37 Sedan beating many cars, even a 335i twice in a 1/8 drag strip (around 1:42 on the vid). He supposedly removed the spare, dropped about 10psi on the stock rear tires. You can see him rev to about 1800 RPM while braking and stomp on it when it turns green:

 

that last race was a touch 1 sided!

 

Nice!
A bit new to me, thinking a coupe was lighter by nature and therefore same engine + lighter car = faster.

But apparently that's not the case.

So if you wanted to rate the stock G37 trims on acceleration capabilities... the sedan with 17's wins, theoretically. Right?

lol

 

Government side impact regulations are a part of it too because without the B-pillar and with longer doors you have to put more into the structure of the doors and body to pass the side impact test.

 

Coupes in general always weigh more than sedans.

 

And don't forget the differences in the transmissions. Auto vs manual, 5 speed vs 7.
Also the G37 is slightly longer than the G35.
And as AZ37 mentioned, Safety specs - as well as vehicle equipment.

While the Coupe is a bit heavier, if you compare like years, models and equipment you will find the difference for a G35 is less than 50 pounds.

 

If you look under the coupe...at least my 10 there's a bunch of useless things that just add weight you can take off. Plastic pieces, tow hook brackets, tunnel brace(there only for the safety of the exhaust not falling down the road & scrapping should it magically unbolt it's-self) Plus the spare & tools, that easily adds up to 50lbs.

 

The doors and the LSD. Larger brakes etc. All on the sport of course.