First of all, I want to preface this by saying that I have respect for most “sports cars” i.e. cars that will do well on the track (cornering, acceleration, and braking) as well as “grand tourers”. Honestly, the 2004 Honda S2000 is my dream car since I think it is a fairly pure sports car, but I am also close to starting a family, so my wife is encouraging me to get the 2005 Infiniti G35 6MT coupe (3450lbs, 298HP) because of the 4 seats. Does anyone know how well the G35 does on the track relative to the S2000? I suppose I’m asking for any personal experiences/encounters at the track or any research you’ve found. This is what I could come up with my own research and syllogism:

The new 298HP G35 now has a very similar HP to weight ratio as the current 350Z. The moderately understeering 2004 and earlier G’s seem to be able to hang with the older S2000’s and 350Z’s in the Best Motoring series.

Best Motoring results:
The 2.0 S2000 and 280HP G35 both ran around the Tsukba (sp?) track at about 1:09 and change with a slight edge to the S2000.
The 350Z and G35 were very close when going against the M3 in one of their battles. The G35 probably had a slight edge in this one instance over the 350Z (although both were beaten by the M3).

From Car and Driver:
BeaveRun Track in Pennsylvania
1.53 mile road coarse lap time / mph
2003 S2000 (2835 lbs)1:10.846/77.7
2003 350Z Convertible (3453 lbs) 1.1164/76.9
2003 350Z Touring (3363 lbs/287 HP) 110.93/77.7
2003 S2000 with hardtop (2896 lbs) 1:11.51/77.0
2004 S2000 (2866 lbs) 1:10.07/78.6

My take on all this is that the G35 can “keep up” with the S2000 on the track. I think the S2000 would do better on short courses and autocrosses for sure. The G35 may be a little more stable on long, fast courses (maybe even faster???)? Any personal experiences/encounters at the track you can point me to? Any research, opinions, or comments would be welcome.

 

Since you're starting a family, get the G35c, but make sure those back seats can take on a baby seat. Also, don't count on using that G35c to shuttle the family around everywhere. Your back is going to be in a hell of a lot of pain reaching in there for your baby.

(2-door + baby = back pain)
Track-wise, you better get the brembo package if it's still available with the G. 3450 lbs will put a good load on your brakes.

After getting my *** handed to me on the track by spec miatas, I'm more inclined to get the G35 sedan, and a used miata for the track.

 

If you've got a baby on the way, go with the G35. Nowhere to put a tyke in the S2K - and you can't disengage the pax airbag either. I owned a 2003 S that I traded in for my 04Z. Both cars are remarkably close, as the track data you posted shows. I think that largely, it comes down to who's drivin.

The S is a momentum car, and the Z is a torque machine. Depending on which car you're driving, you're going to have to look at the course rather differently; but if you've got your **** together, then it'll just be which car fits you better.

 

I saw a very nice G35 at the track in Maryland this weekend. Once they post the results you can check it out at www.wdcr-scca.org and click on "Autocross" and then "preliminary" once the link opens. Somewhere in there is the G. (Note: it has a LOT more to do with the driver than the car)

Had they made a convertible G35, I would have bought one for sure! Coupe, not the sedan... sedan is ugly until they put the coupe body on it like they should've done in the 1st place. Sorry... let some subjective emotion in on that one.

Boiled down.... G35 is a great buy

 

the S2k is set up better than the g35. weight affects the quick handling transitions that an autoX circuit offers. But if u're just an occasional autocrosser, then a g35 is fine as long as your expectation is to have fun and don't mind getting handed over by the 'hard-core' cars.

 

For autocross, I agree with you...the S2K seems to be a juggernaut that can't be stopped...it's almost ideal for that. I do mind if I can't even compete with the best of them, but I figure I have a long way to go before I can even become a little bit competitive with the best of them.

The S2K>350Z>G35 in autocross. I think having low weight, little understeer, and a short wheelbase may all contribute to that equation.

I think on the track these differences become less pronounced. Look at the track times listed in the first post by Best Motoring and Car and Driver. The difference in weight between the 350Z (touring) and G35 (03/04) is relatively small today (about 100 lbs without the G's sunroof, maybe about 180 lbs between the G and Z Track). The 298HP on the upcoming 2005 G35 makes the hp/weight ratio about the same as the current Z (right between the Z track and touring models). The long wheelbase was said by the Best Motoring guys to contribute to greater stability and cornering on the track...I wonder if that's true. Regardless, the G seems to already be about the same as the Z on this track and can only become more "equal" with the extra HP. Are my conclusions reasonable or a bunch of malarkey?

 

There is a guy who attends most of the local AutoX events driving a S2K who pretty much dominates the rest of us in BS. I talked to him at length on Monday and found out he has an AutoX setup that takes advantage of every allowable Stock modification. He runs lightweight wheels with Hoosier racing tires. He has shocks, front sway bar and has the camber and toe-in set to ideal values for racing. It's not a daily driver - it's purely an Autox car. He is also a championship level driver. All that makes him about 7 seconds faster than the rest of us in BS cars.