I recently noticed my car's RPM is quite high. My car is 2007 G35x with Auto Transmission. Below are some data of Speed (MPH) and RPM I noticed.

50MPH ~ 2000RPM
70MPH ~ 3000RPM
80MPH ~ 3500RPM (This one is probably a little below)

I have driven other V6 cars in my rental car experience (e.g. Ford taurus, Chevy impela, etc), and from my impression all (or most) of them have a lot low RPMs (something like 80MPH ~ 3000RPM, not sure about the the exact data). I also saw posts in this forum of G35 with much lower RPMs (probably not 2007+ model).

I was quite surprised of my car's RPM. From the RPM, it's like a 4-cylinder car. I also heard that low RPM usually means long engine life and it's the main reason 6-cylinder lasts longer than 4-cylinder. I asked my dealer about the RPM. And he said it's normal because new G35 has more horsepower, blah blah, etc, which I am quite suspicious.

So how's your G35's RPM, guys? Please correct me if my understanding above is wrong. Thanks very much in advance for your replies.

P.S. I bought my car in August 2007, and I absolutely love my G35. It brings me so much fun driving it.

 

Correct and known
May contribute to G35 poor gas mileage
Discussed at length in various threads

 

I couldn't find any post using key word "RPM". Do you still know the link to those discussion threads?

Well, if RPM is normal, is it bad for the engine driving at 80mph for an extended period with RPM at 3500? I think the best RPM for engine for a long driving period will be below/around 3000. Am I right?

 

Keep in mind this is a high revving engine. It does have a max RPM of 7500. The Impala and most other crappy V6 engines in rental cars should have about a 6000 RPM redline.

Its like me complaining of having an RPM of about 3500 at 80 mph when a diesel engine does it in about half that.

Engines have varying redlines for many reasons. If an engine has a high RPM redline, that just means that the engine has stronger internal components to prevent it from suffering from fatigue stress and snapping in half. Typically smaller engines have higher RPM's as well. Although I'm sure most rental car V6's are about 3.5 L or smaller but the amount of R&D that goes into engineering our motors is far higher than what goes into those. Lower RPM engines don't necessarily last longer than higher ones. As long as you avoid over revving your engine, you'll be fine.

To compare, the new M3 has like an 8400 RPM redline so I can't even imagine how high that thing revs crusing down the freeway.

So in short, cruise at 4500 RPM if you want to, the engine is more than capable of handling it. The VQ35HR engine loves to rev...hence the HR in the engine code (high revolution/high response).

 

I think 3k is ideal for crusing because it doesnt drink too much gas and still is close enough to the power range to pass others as needed... The AT will be around 3300 revs at 80 mph.. like others said, that doesn contribute to bad mileage in the G but its also one of the reasons why the G's perform well, they are designed that way for performance

 

its just the gearing thats all. Those rental cars you drove are probably 4 speed autos with taller gearing. Constant 3500 RPM is not bad for the engine, gas milage may suffer though.

 

Wow, thank you guys for all the explanations! I feel much better now with more understanding from you guys.

 

Low gearing = fun on the street. it's the ONLY substitute to cubic inches or FI.

 

At 80Mph the RPM should be @ around 3200 rpm. This has been discussed before. Our HR is a shorter stroke high revving engine which redlines at 7500 RPM. 3200RPM when cruising at 80mph is completely normal.

 

wont hurt car. gas mileage suffers due to it as others have said. The simplest fix would be the 09 G35 Sedan 7-speed tranny. Something we can all use. Should put the top gear 80 mph cruising rpm at somewhere around 2600 to 2800 in my estimate, using Lexus as a benchmark.

 

80mph@2600-2800. Man that would be so nice......as for your estimate, take a look here:
http://nissan.iconicweb.com/assets/s..._NNA_Final.pdf
the top gear will be either 0.7715 or 0.7715 (it's a safe bet that Infiniti will share this new transmissions will all its vehicles across the line). In the real world; the overall gas mileage may go up maybe 1-2 mpg. I'm not an expert on cars and gearing; but given the broad torque range of the VQ, why in the world couldn't Nissan design the 7A with a lower overdrive ratio like 0.67?

 

people say it redlines at 7500, but what they don't know is it redlines at 7600! just 100 more rpms to 'waste' gas (wasting gas=fun, lol)

 

Sure all the above factors contribute to poor gas mileage, but there's no doubt about it that they are other cars with the same HP or more (V8s, etc) that get similar gas mileage or better.

My good friend has a C5 Vette (5.7 V8), which is clearly geared/made strictly for performance and it gets around 19-21MPG, whereas I'm getting the same. Obviously the weight difference makes a dramatic difference, but that's one of the few downsides to our cars...they love gas.

 

Driving in the tiptronic seriously KILLS my mpg. REDICULOUSLY. Although, I do drive it hard when using the tip. When you get this car, you have to understand: Soccer moms drive it and think its an everyday pu$$y car, like a top end accord/maxima, just with more luxury features. That is not the case my friend. You can run with a 330xi, even through the twisties, Loose a TL like you could never really imagine, and pull some great power moves in traffic---especially for a sedan. If you drive it like that soccer mom you'll get that 18 mpg we see at the end of the rainbow. If you drive it like a car lover should. You will see much lower. Its the price you pay to have that much fun with your clothes on.