I'm considering purchasing an A3. It will be a small step down in size though from my Volvo S60R. I'm wondering if I'll miss the room. I have a 7-yo and 9-yo so back seat room is not an issue. A rarely carry adults in back. When we need cargo space we take our SUV. When I'm alone going to Costco or Home Depot I can put the seats down and wa-la, lots of space right?

I was considering an A4 but I can't believe how much better value the A3 is. A comparably equipped A4 is what $5K-$6K more? And what do you get for that? Essentially the same engine in a 400-lb heavier car! No DSG transmission option! No Sky moonroof? No magnetic adjustable suspension? It would seem the only reason to buy an A4 over and A3 is you want more room? That's some expensive extra room! Am I missing something?

 

The A4's engine is not the same as on the A3. It has a little more power and alot more torque.

With the A4, you can get torsen based quattro, which is completely different from the Haldex based quattro on the A3. You could move into the sportier S4, which then has the S-tronic, along with torque vectoring sport differential.

 

I didn't realize there is that much of a torque difference stock. I would expect it is primarily to do with the air/fuel, timing and throttle mapping of the software. I know for like $600 you can get a remap for the A3 ECU bringing HP to around 250 and torque to around 290ft-lbs so it is obviously very easy to up the torque on the turbo engines. Both cars have the same displacement 4-cylinders. I wonder if the head or the turbo is different on the A4?

I don't see how the S4 could even be mentioned in the same post discussing an A3 or even an A4. That's a pricey car relative to the other two. What is an S4, about $15-20K more than an A3?

I'm very interested to hear about the specific differences in the two AWD systems and the pros and cons for each. I would guess the differences are there but the resulting benefits for either system compared to the other aren't earth shattering.

I heard such great things about the DSG transmission and would love to retain adjustable dampening on the suspension like I'm used to in my S60R. I know you can get that on an S4 (which is in another solar system price wise as I mentioned), is it an option on the A4? The A3 is a bit smaller than I'm used to but at that price, I still think in general it is the best bargain for mid-luxury European cars and still think compared to the A4 Avant it really makes you look like you are paying a lot of money for some more room and a higher number on your badge. I own neither so I'm unbiased. I'm just comparing the two on paper including price.

 

The A4 has Drive Select, which includes adjustable suspension, but doesn't have the S4's dual clutch transmission or sport differential.

The Audi's A4 (and higher)'s torsen based quattro is 'permanant' AWD, meaning all wheels are being driven, and loss of grip in the front or rear will not cause the other axle to turn less (as in open differential), or wait for a slip to occur first (as in A3's clutch based differential). So you have grip all the time.

The A3's are clutch based, with the clutch being mostly open and engine driving mostly the front wheel until the front loses traction, then the clutch closes and transfers torque to the rear wheel. So that momentary loss of traction creates that feeling of loss of control before the car regains control. But if you were cornering and the car's direction was very different from where the front wheel were pointing, and the front wheel loses traction, the time it takes to transfer of power to the rear wheel might be a bit too long given the momentum of the car in the direction it wanted to go, making regain of control quite a bit harder that the slight slip in the wheel.

 

From what I understand from '09 forward the A3 uses the gen 4 version of the Haldex system. I was so curious I just spent an hour reading about the difference between the Torsen and Haldex. I concluded that it appears to be a toss-up as to which system is 'best' as best really depends on the application and any 'gap' between the performance of the two has become quite narrow due to the advancements with the Haldex. It appears the gen 4 Haldex is quite an improvement. I was surprised they are using the system in the Porsche Carrera. Based on what I read both systems are excellent so I wouldn't mind having either. If you haven't read about gen 4 Haldex, check it out, it's quite interesting.

 

I had a loaded 2009 A4 2.0T Quattro loaner for 2.5 weeks while the DSG Mechatronics in my 2006 A3 was being replaced under CPO warranty (fantastic improvement BTW). Very nice to drive, more luxurious feel than the A3, lots of electronic goodies (no Drive Select, however), nice amount of rear seat space that my car pool appreciated (MUCH bigger than previous gen A4s). But I was still happy to get my A3 back.

They are very different driving experiences, with the A3 feeling more agile and generally fun, while the A4 was more 'solid' and refined. I do wish that the A3 leather seats, brake feel, dead pedal location, cup holders and stereo (Bang & Olufsen in the A4) were like the A4's. And I really liked that back-up camera in the A4. OTOH, the magnetic adjustable suspension in the newer A3's would very nice, especially since my front Koni FSD's seemed to have lost some of their rebound damping after only 28K miles.

I strongly suggest that you drive both of them and decide which feels better. If I was buying now, I'd start my shopping with an A3 TDI and Mazda 3 (if I could get used to that "happy" front end look).

 

The fact that you are recommending looking at a TDI and didn't mention anything about the A4's acceleration leads me to believe something like 0-60 performance isn't important to you, and that is fine. The A4 is 400 lbs heavier with about the same HP and some more torque so I imagine it feels a bit sluggish compared to the A3 when going 60-80 on a highway to pass. The more nimble handling feel is also probably due to the 400 lbs lighter car.

On the stereo isn't there an option for a better stereo in the A3? If so are you comparing a stock stereo to the A4 B&O or the premium stereo in the A3 (assuming there is one) as a very good stereo is very important to me.

I was looking at a Mazdaspeed 3. I thought it had AWD, correction, think it is only FWD and no leather, no heated seats, etc. I've got to draw the line somewhere.

 

The Gen IV Haldex is not very different from the Gen II on the pre 2009 A3's. I think it includes a accumulator pump so pressure to the clutch could be applied even without a rotational difference between the front and rear wheels. In the Gen II environment, there is always a difference in wheel rotation unless you are going dead straight, and there is definitely enough of a difference in wheel rotation during turns.

I think the issue with stock Haldex is that it does not actively engage AWD unless there is a loss of traction, and when it does, it does not engage fast enough (at least in Gen II). That is why they have the sports controller, which pre-engages based on how aggressive you are driving the car, and it has bigger valving to allow the engagement to be much faster.

The Torsen is a never slip model that is not available anywhere else besides the HUMVEE military vehicle. Plus Audi's planetary model allows power to be delivered more to the rear than the front 40:60. The best a conventional center split diff could do is 50:50. To go beyond that, you would have to have a inverted setup like the Datsun GT-R, which has a shaft going to the rear to drive the rear wheels, then a F/R differential to send power back to the front.

As dfrost said, you have to drive it to see if it is enough of a difference. If condition for testing allows, drive in low slip condition like full throttle in unplowed street, or taking corners very fast in the wet, preferably with ESP on and off so you know when it is the ESP pulling you back and when it is the quattro.

 

0-60 capability is interesting, but less "real world" to me (but I'm in the 'more mature' age range). But rolling acceleration (30-80 mph) where torque matters, is more relevant for the driving I do. All reports of the TDI says that it is phenomenal there, and I can imagine that it is a great combination with DSG. I don't recall the 2009 A4 feeling "sluggish" at all, just less fun, but much better than earlier generations of that model.

I have the Bose Symphony stereo upgrade in my A3 and it's not great. The "sub-woofer" is only 5" while the door speakers are 6.5". (I've installed a switch to disable the sub, and often find I like it better off.) The Bose also overlays non-defeatable auto-adjustments that don't always agree with my tastes, and makes speaker upgrades difficult because of the low impedance design. The Bose system in my wife's Mazda6 wagon isn't quite as wierd, but it is nothing special, either.

Since "very good stereo" is impotant to you, another difference between the A3 and A4 is interior noise. The A4 is much better there, even with the notoriously bad tires (Pirelli P6) that Audi tends to install OEM. I'm looking forward to replacing the now noisy Toyo T1-Rs (nearly new when I purchased it CPO with 25K) with quieter Michelin PE2s next spring.

The Mazdaspeed3 is pretty intriguing, but I was actually thinking of the non-speed Mazda 3, which does have leather, heated seats (which I don't have in my Arizona-sourced A3) and many other nice features as standard. It has enough legroom for leggy me in the new version, unlike the previous gen Mazda 3. I haven't driven one, but I've been quite impressed with the driving characteristics and interior space of my son's 2003 Protoge5. I'm much happier with my A3 after the DSG Mechatronics upgrade, so not really shopping now.

Regarding AWD versus FWD, I'm a firm believer in using four winter tires. On my non-traction control BMW, they transformed that car into an acceptable ski transportation car.

 

The 2.0 on the A4 utilizes Variable Valve Lift, which the A3's 2.0 does not, hence the increase in power and torque.