[Bob in St. Louis]

The 19 may be quieter than the 18 because the manufacture changed the tire brand/model/performance rating between the two???
But if he can't get hard statistics, then it's probably just his opinion and not based on information given my the manufacturer.
Also, the car with the trim and/or performance package that comes with the 19 might be stuffed with more sound absorption than the 18?
I'm speculating here, just based on past experience. I do not know specifically of what Mazda is doing.

But leather absorbs more noise than cloth?
Well, acoustics aren't my forte, but I'm thinking that (again), a cloth interior car is a base model than has less interior sound absorption than a leather clad interior.
Seems the masses demand leather and cloth is for the poors. For some reason. It's hard to find a high end car or trim level that contains a cloth interior, so if you want cloth, then you must  have less money to spend on a car, therefore it won't be as quiet as a "richer" car (within the same model line).
So yea, I can see why he would say that, or at least how he came up with his opinion.

[JLM]

I'm with you Bob, prefer cloth to leather upholstery.  The salesman is problem inventing reasons to sell an upgrade, but I suppose there is a slight chance that the leather option has more padding and so slightly lower noise levels.  Remember a secretary at work put towels on her leather seats in the summer.  Her husband had won the car (the last Buick Reatta built, British racing green with tan interior).

This whole discussion is a bit ironic to me.  30 years ago was shopping for a new car and test drove an Acura Integra with manual tranny.  Darn engine was so quiet and smooth I ground the starter not realizing it was already running and then had to use the tach to shift as I couldn't hear the engine rev.  That and a crummy trade-in offer soured me on the deal.

Actually like the growl of my Subaru boxer engine so I can monitor the engine without looking at the tach.  My 4 cylinder Camry is quiet and can hardly hear the engine.

[JimJ]

I wouldn't buy 19" wheels simply for the reason that it's an odd size, and tires for it tend to be ridiculously expensive. 17s (or 20s, for that matter) are a lot cheaper.

[*Scotty*]

Frank, if take you any more test drives be sure to get the car over 55 or 65 MPH. I rented a 2007 Subaru Legacy FWD and it was fine around town even up to 35MPH, but once I got it up to highway speeds on the interstate it was very NOISY. Transmitted noise and vibration were unacceptable. I rented a Toyota Corolla in 2008 that was amazingly quiet, my wife and I just looked at one another in disbelief, it was as quiet as much more expensive cars.
Scotty

[Mikeinsacramento]

Frank, if take you any more test drives be sure to get the car over 55 or 65 MPH. I rented a 2007 Subaru Legacy FWD and it was fine around town even up to 35MPH, but once I got it up to highway speeds on the interstate it was very NOISY. Transmitted noise and vibration were unacceptable. I rented a Toyota Corolla in 2008 that was amazingly quiet, my wife and I just looked at one another in disbelief, it was as quiet as much more expensive cars.
Scotty

Subaru has never made a FWD Legacy.  They are all mechanical, full time AWD.

[Mikeinsacramento]

Well...Ok, now I'll chime in...
AWD is only FWD unless front wheel slippage is detected, then the rear wheels kick in. So yea, while AWD does technically have more moving parts, half of them aren't doing anything under the vast majority of driving conditions.

That's not entirely true.  Audi, Porsche, and Subaru all use full time, mechanical AWD.
There may be others, but relatively speaking, it is rare.  Even Lamborghini uses Haldex.

I suspect the idea leather interior is quieter, may be due to it being part of a higher trim package, which by default may also include more insulation. 

[Bob in St. Louis]

They mechanically run all four wheels all the time? Like a 30 year old 4x4 truck? 

[JLM]

Frank, if take you any more test drives be sure to get the car over 55 or 65 MPH. I rented a 2007 Subaru Legacy FWD and it was fine around town even up to 35MPH, but once I got it up to highway speeds on the interstate it was very NOISY. Transmitted noise and vibration were unacceptable. I rented a Toyota Corolla in 2008 that was amazingly quiet, my wife and I just looked at one another in disbelief, it was as quiet as much more expensive cars.
Scotty

Huh.  I own a 2009 Subaru Outback (currently with 133k miles on it) it seems to be noisier at lower speeds where I can hear the boxer engine "growl".  Note that it has a 4 speed automatic.  Also owned a 2009 Toyota Corolla eventually with 153k miles on it, also with a 4 cylinder & 4 speed automatic, that was quieter but more underpowered.  Just replaced both rear wheel bearings on the Outback that I could hear at 40 - 60 mph, wonder if that was what you experienced?  Both are/were good cars, but the Subaru requires more maintenance (and at much higher prices via the dealership).  The Subaru feels more substantial, my Toyotas (now have my 3rd Camry) have more of a precision feel and also get better mileage.

Yes, except for the BRZ, all recent Subarus use full time, symmetrical all wheel drive.

[RDavidson]

Yes, except for the BRZ, all recent Subarus use full time, symmetrical all wheel drive.

Yup....and I'm pretty sure they've been this way a long time. I would go as far as to say that Subaru's AWD system is their main point of market differentiation. Without it, they're basically just another auto maker.

[Bob in St. Louis]

I stand corrected on the AWD thing.    I would have never imagined they'd do that.

[RDavidson]

They mechanically run all four wheels all the time? Like a 30 year old 4x4 truck? 

Actually, what you describe is "full wheel drive." For a long time I didn't know the difference either, until a friend explained it to me. Here's a good, short, explanation.
http://www.digitaltrends.com/cars/whats-the-difference-between-four-wheel-drive-and-all-wheel-drive/

[Bob in St. Louis]

Yes. That's what Mike said in used in some modern cars on post #25.

[RDavidson]

Saw that, but your question is post #26, so it made me think maybe Mike didn't provide enough detail in his explanation for ya.

[DaveC113]

Yes, except for the BRZ, all recent Subarus use full time, symmetrical all wheel drive.

True, but there are big differences between models. The "symmetrical" thing is marketing bs. The auto-trans cars are 90% fwd until they slip, then a computer controlled system transfers torque. On manual trans cars there is a viscous coupling, which is fully mechanical and has a 50/50 split... with the exception of the STi, which features a computer-controlled center diff whose torque-split is driver-adjustable.

The STi is only car that is truly "symmetrical" though as it's the only car Subaru offers with front and rear limited slip differentials. The other cars have traction control, which avoids wheelspin through applying the brakes, but that's more of a band-aid than having real limited slip differentials. The STi's drivetrain and brakes are very impressive but unless you're taking it to the track it's overkill vs the WRX, which offers very similar performance in most circumstances.

 

[Bob in St. Louis]

Saw that, but your question is post #26, so it made me think maybe Mike didn't provide enough detail in his explanation for ya.

Yea, I've given up. I'm good. 

[JimJ]

Actually, what you describe is "full wheel drive." For a long time I didn't know the difference either, until a friend explained it to me. Here's a good, short, explanation.
http://www.digitaltrends.com/cars/whats-the-difference-between-four-wheel-drive-and-all-wheel-drive/

I know that's probably not written for car people, but it's somewhat too-overly-simplified in that it equates normal 4WD systems to a locking differential.

The difference is not small:

https://www.youtube.com/watch?v=mkSiJ3UZlso

[bladesmith]

My AWB rig is 60/40. On all the time. Because the rear is slight lighter than the front, it allows the rear to act slightly like a rear wheel drive when corning. If you know what I mean. The rear will come out slightly when corning, but not out so far it gets out of control or spins around, like a rear wheel drive.

The tires probably produce the most amount of road noise. it seems that I have noticed differing amounts of road noise with different brands. Michelin being the quietest of all brands bought.

The fact that my rig was built on a truck platform does not help road noise, I guess, I know the 2006's were built on a newer lighter frame and are lighter/faster and overall a much quiter rig, basically a completely different rig. My 2005 is heavier, and I think that produces more noise, because of the fact that a heavier rig produces more friction, where the rubber meets the road. (IMHO).

Good luck,

V...

[RDavidson]

I know that's probably not written for car people, but it's somewhat too-overly-simplified in that it equates normal 4WD systems to a locking differential.

The difference is not small:

https://www.youtube.com/watch?v=mkSiJ3UZlso

True. It is a very much a layman's explanation. I posted it for that reason, as not all of us are major "car guys" perhaps including the OP. Sometimes getting too technical can be confusing when only a basic understanding is all that is required for the topic of vehicle noise (mechanical, wind, road, etc).

[DaveC113]

AWD vs 4WD is super simple. 4WD uses a transfer case that transfers 50% of the power to the front and 50% to the rear all of the time. AWD uses a differential between the front and rear axles and is capable of slip and transfer of power front to rear, which can be accomplished mechanically (torsen or viscous coupling usually) or with a computer controlled differential. Some AWD systems have a locking mechanism for the center diff, converting the car to 4WD which is effective in low traction situations or if the car is stuck.

Lockers or limited slip differentials on the front or rear differentials are a totally different topic and can be used by vehicles with awd or 4wd systems.

If you want specific info about what cars use what system, and how they work in detail... here you go:

http://www.awdwiki.com/en/home/