Got a 2013 G37x as a loaner from the dealer

[aiham78]

My car is 2011 M37x with 36K miles, I was complaining of bad bluetooth phone call quality. I dropped it at the dealer to replace the bluetooth microphone, they gave me 2013 G37x with 400 miles on it.
I noticed that this car has better acceleration than my car, it is fast. I asked the mechanic about that and he told me that my car is better but heavier in weight so that's why it doesn't accelerate as fast as the light G37x.
I'm not 100% convinced, do you guys have an explanation of that? Do you have any recommendation to improve the car's acceleration? Like cleaning the MAF sensor or something else.

Thanks,

[mexillis]

The weight difference is only 200 lbs and the gear ratios are about the same. Do you drive it as hard as you did the loaner? Does the exhaust sound the same? Maybe a few placebos affected your judgment and that's what happend...?

[Larz]

I would expect the G class to accelerate faster as well. The horsepower per ton ratio between the two cars clearly would favor the G class. Given the same conditions, same roadway, same crosswind, etc ... physics says that speed and inertia are proportional to 'the amount of mass' to which the same force is applied.
There is also something to be said for the age and wear levels between the two engines. a car with 400 miles and 3 less years on the road would be expected to burn fuel more effectively, have less gunk in the engine parts, and perhaps a tighter transmission. Then there is the gear ratio and tire size which I reckon is different between the two cars.

When I use a G class as a loaner, I feel the same differences. But that doesn't impress me because the rest of the car is so much 'less' in many ways: harsh ride, more plastic inside, less luxury, noisier in general on the road. And even with more acceleration, the G transmission is easily confused. It's as if the car isn't sure which gear to use based on what you do to the gas pedal - running quickly between gears before deciding which gear is needed.

The Q50s Ive driven are similar regarding harsh ride and a gear box that's frequently confused, but they are better looking and don't seem as 'cheap' inside as the G class.

Having blathered on about that, we also need to remember that the G-class is designed as a 'sporty' sedan and the M class is not (even though some claim it is). The M class is designed to be more comfortable / luxurious while providing good throttle response and good acceleration.

[TDot]

I agree the G feels better and accelerates better. I never noticed the gear issue of it no knowing what it wanted to do...however, I would say that statement definitely applies to all the M I've driven. But I'll take my M everyday (over the G at least) strictly because of the interior.

[GQM45s]

+1 for the G - it felt the same for me when i had a loaner, but then again you might consider the X factor - the AWD - they tend to launch faster than RWD from my experience in STIs and EVOs i've driven

[Larz]

+1 for the G - it felt the same for me when i had a loaner, but then again you might consider the X factor - the AWD - they tend to launch faster than RWD from my experience in STIs and EVOs i've driven

That's a valid point. Sales people tell you an X model (AWD) will be much more stable in wet and snow. Not all that much better, really, but better none the less. They don't tell you that AWD vehicles lurch forward from stops or that they don't ride or shift as smooth as a RWD model, or mention the increased fuel consumption and maintenance costs.
Not poo-ing on AWDs but I would have to live in a place where heavy snow or rough terrain was a frequent thing before I'd go for any AWD vehicle. In South FL it's simply not necessary and it decreases the 'fun' of driving.

[psyopper]

AWD Infiniti X models are not a full time AWD. ATESSA ET-S is selective variable AWD- default RWD until the stability control computer detects slip, then electro-hydraulically engages the center differential to add drive to the front. Under a 0 slip condition the fronts are not driven at all, and as slip increases the computer adds pressure to the center diff to proportionally increase drive to the front. The split limit is 50/50 when fully engaged.

This system was originally developed for the Nissan Skyline GTR R32, and it's successor, ATESSA ET-S GTR is on the current Nissan GTR. This system uses a similar split system but allows the GTR to control slip both longitudinally (AWD) as well as laterally across the axles.

In the 0 slip condition there is no parasitic loss and other than the extra weight (of 200 or so lbs loaded center-front) so it should have no effect on performance or fuel consumption.

EDIT: The reduced fuel consumption numbers for the X models comes from the higher final drive ratio, which I believe is intended to compensate acceleration for the additional weight at the cost of fuel consumption.

[White-Rush]

I had a Q50 as a loaner a few weeks ago, and it felt really quick off the line, but while rolling on the HWY it didn't feel any stronger than my 37. However, the one place it did perform exceptionally well, was the handling. Even though i have coilovers on my M, the Q50 felt soo much better when pushed hard in turns and curves...

[psyopper]

Coilovers are excellent for corner balancing race cars or setting ride height on a road car. Sway bars are where the money is made in cornering by tying suspension load laterally across the car and keeping it flat when you load the outside wheels.

Does anyone even make a sway bar kit for the M's?