I'm willing to bet that the difference in MPG at 33mph between 4th and 6th is negligible if not slightly worse in 6th since the car is to far under the power band. Any attempt to accelerate the slightest bit in 6th at 33mph will result in far worse fuel economy.

 

Hence, cruising... if I need power, I will downshift.

 

You clearly missed the point of my last post. There is no avdantage to being in 6th gear at 33mph

 

but there really is no DIS-advantage either...

 

besides having no power at your disposal without downshifting

 

isn't that the point of the M/T? If you don't want to shift then get an A/T

 

you should be in 4th, 5th is your passing gear on the highway, cruising gear in the city.

i mean even the auto isn't in 6th gear @ 33mph. it's in 5th.. of 7

 

If you are trying to simply maintain a certain speed (cruising...not accelerating/stopping), then 6th gear will give you better MPG than 4th or 5th because the resistance from the drivetrain is less. The less drivetrain resistance that is slowing the car down means less fuel is needed to keep the car moving at that same speed.

I tried 6th gear on my drive home (at about 33MPH) and I felt like I was driving a Geo Metro whenever I had to speed up! lol But when I was cruising at a fairly constant speed, the computer said I was doing crazy good MPG...too bad I bought this car because of it's go power (and good looks).

 

I've done it here in Houston in traffic. It's doable as long as your just coasting along. Have you ever realized just how little it takes to keep your G rolling, just rolling at 33-40MPH ? Why be in a lower gear just to be using a little more fuel and turning the engine faster when all it takes is the slightest bit of energy just to keep moving at that low speed? The speed is not meant to accelerate from, only for rolling along like I do here when traffic is bad for a wreak or construction etc. There are no hills here so for the most part you could almost coast through most situations. When I encounter ramps or know I will need to accelerate I will use a lower gear, it only takes a short moment to shift. I can get over 26MPG in town. using the low speed high gear techniques.
On the other hand when cruising at 45-50MPH in 6th then dropping to 2nd and red-lining each gear is the best rush you can get so don't think I always lug around town.

It's all relative to the situation, how you feel and what you want to do. It does not hurt the engine whatsoever, the G37's engine is way tougher than you may realize. The same bottom end and many other components are used in the GTR.

 

I think it is important for everyone who drives a manual transmission to understand that lugging an engine is harmful to it. There are two issues that come immediately to mind: 1- the potential for low oil pressures, which can cause premature rod/crankshaft wear. 2 - the thrust face of the pistons can come into contact with the cylinder walls. Piston skirts have even been known to break and cause all kinds of cylinder damage on engines that have been lugged a lot.

I'm not saying this is going to happen right away, but anyone who makes it a habit of lugging his engine on a regular basis can definitely do some internal damage.

 

Cruising, I'm at 6th usually around 40mph. 33mph isn't unreasonable IMO, especially going on a flat road.

 

Lugging is driving 25MPH in 6th. Are you trying to say driving 33-35 is lugging?
If your saying that, why would it be in the owners manual? I've been driving manual vehicles since 1978 and a few of them for hundreds of thousands of miles using the low RPM techniques when just rolling like Infiniti is intending with no problems whatsoever, so I say you should clarify what you mean by lugging.
Yes I agree, lugging will hurt the machine, but your not lugging at 33MPH on a flat surface when needing no acceleration. I also agree that accelerating from 33MPH can cause undue stress to the engine and transmission for a short period so I downshift before I accelerate because it's natural. and you should too.
My 2010 loaner 7 speed automatic behaves in a similar way. I went out and tested it this morning and notice when just rolling at 33MPH the RPM's drop to nearly 1200. The 7 speed is behaving the same way. When accelerating from that low speed, it drops more that one gear and the RPM's come up quickly so it does not lug. (Car is in for maintenance and a new rear speaker today)

 

To me, lugging occurs whenever the throttle is opened and the vehicle doesn't accelerate or barely accelerates. If I'm at 33 MPH on a completely flat and level road and I floor the accelerator, the vehicle will barely accelerate until the RPM climbs. That puts tremendous stress on the engine.

Think about riding a 10-speed bicycle up a steep hill in 10th gear. The stress on your legs/knees is much greater than if you were in a lower gear. It's a silly comparison, but it is one way to think about it.

 

Again, you buy a MT to shift yourself... if that's too much effort, you have little to lose by staying in a lower gear.

Some of us prefer to use our MT to the fullest; we're not accelerating at 33mph in 6th.

 

I think we're past that point in the conversation. Anybody can put a car in gear at any speed, but that's not the point here. Dropping down a gear to two to accelerate is always fun