GoCougs

I have a 2011 G37x sedan w/40k miles in for service. I received a 2012 G25 sedan w/8k miles as a service loaner. In sum total the G25 is significantly more responsive making for a much more pleasurable drive in in-town and moderate driving.

Brakes: G25 has a nice stiff pedal with short travel. My G37x has much more travel and is spongy. In fact, if don't pay attention to keep the brake actuated when at a stop the car will creep forward. I've had many close calls at long stop lights. Any other AT car I've had simply the weight of the foot will keep the car from creeping (including the G25). I had brake fluid change and new rear brakes ~5,000 miles ago. No change.

Transmission: G25 responds much quicker to throttle inputs. Just a bit of throttle and the G25 will loosen the converter and then seamlessly downshift. The G37x however will simply bog and will require 1/2 throttle before it will downshift. (This is in D - I never use DS.). I had the reprogramming via ITB12-027. That mostly solved the issues listed within the TSB (especially lousy rev matching on downshifts)

Throttle: G25 has much more aggressive throttle mapping and in conjunction with a more responsive AT, is actually a quicker and more enjoyable drive at up to 4/10s. The G37x however needs comparatively more throttle input and and shifts are lazy and laborious.

I know the G37x sedan weighs ~300 lbs more and has AWD gear but I can't imagine it having the above effects on brakes, transmission and throttle. As far as I can tell they have the same brakes and similar gearing but of course the G25 is down well more than 100 hp.

The dealer is at this moment checking both the brakes and to see if there are any more transmission TSBs. My 90% hunch is they'll come back with NPF, which is quite disappointing. The G25 is simply a more enjoyable drive at 4/10s and below, and it shouldn't be.

Thoughts anyone?

kanariya

One of my main complains on my previous G37x.
People here thinks I'm a fanboy of _________.

Black Betty

iTrader: (60)

Sounds vastly implausible.

Eldan

Sounds like you need your brakes bled or check the master cylinder. I think the throttle and brake problems you mention are specific to your car.

blnewt

iTrader: (13)

Had a G25 loaner a while back (when I got my AT TSB applied) and that thing sucked ballz, not enjoyable at any speed. Maybe the brakes were OK but at that point I didn't care
Never happier to get my car back from the service bay

blazeplacid

iTrader: (1)

I also drove a G25 when I was looking for my G37

I didn't think they were any different in terms of braking or transmission.
They are pretty close to being the same car.

Sounds like you are experiencing the placebo effect

xdime00

iTrader: (1)

I think placebo effect or just problems with your own car. Maybe try another G37 to compare to your car?

Yan141

iTrader: (3)

I never had any issue with my 09 g37x sedan.

GoCougs

Just got my G37x back. Obviously a lot more power but it just isn't as responsive as the G25 in day-to-day driving. I had ~100 miles in the G25 loaner over two days, and I'm a big (knowledgeable ) car guy to boot. The difference is there unfortunately. If there was anything materially wrong I'd be getting engine and tranny codes.

In response to my complaint about the response issue the service advisor says it's a common complaint and that Infiniti is working on another TSB for G37 AT programming. I have my doubts though now that the Q50 is just around the corner. As to brakes, I'm going to take it to the local independent tire place to have then do an inspection.

Another notable aspect of the G25 is the 2.5VQ is a smoother, rev-happier motor, which I think also contributes to better, albeit subjective, driving response.

MalbecG37S

Brakes - I agree with the other posters - sounds like they need to be bled.

Response - try an ECU reset - see if that resets your perception

ilovemyg37

i got a g25 as a loaner car a few months back, i had no idea as it looked like a g37 sedan at first glance to me.

then, i accelerated.

then heard a loud noise from the engine (possibly revs), looked out the window, and i was barely moving! i was like wtheck is going on! i can only describe it as trying to drive in a river made of jello.

later that day, i saw the g25 symbol on back, googled how much horsepower a g25 has, and everything made sense after that

hechen507

iTrader: (5)

Last summer I had a loader G25X for my G37x for a couple of days and I would say my experience in it was quite the opposite as yours.

I admit the 09 x tranny could be not responsive sometimes but it not an issue for me at all. I am use to my G and the tranny characteristic is very predictable for me. If I want to downshift I mash the pedal more, if I want to stay in gear I would know the how much throttle it can handle before shifting, and if I want to up shift I either lift off a bit. I also have paddles, but I find myself using the bump stick a lot more.

When I drove the G25x the first thing I notice was the decrease in power especially high end power of course. But I also notice that the power band is a lot more linear than my car. The transmission also felt smoother/less aggressive, but this could be because linear power band. The G25x felt underpowered for sure and you could really feel the weight the car because of it. I honestly didn't enjoy driving it and just parked it most of the time....

trcb777

Sell your G37 and get the G25

GoCougs

Actually, the G37x was neck-n-neck with a B8 S4. At the last minute I sided with the more reliable choice but regretting it now. I'm disappointed in the Q50 (primarily no engine or tranny upgrades but also styling) so that definitely isn't going to be my next car.

PAULY_LONG

Make sure the snow switch isn't activated on your G37x?

Honestly, this sounds specific to your car - are you the original owner? Brakes definitely sound like they need some attention. After a day of drving a G25 loaner, my '10 G with 19K miles feels MUCH more responsive to throttle inputs and takes a little readjustment.