Originally Posted by mirin S6

Not true. Here is a relevant response from a physics forum.

Originally Posted by feralc

I believe rhit's commentary of "The TDI in D mode, felt like the TFSI in S mode. " was actually in favor of the TDI not against it
Like he feels the TDI responsiveness in regular setting D as responsive as the TFSI in S

Originally Posted by perlfather

This is a good explanation, however .....

Let's look at the simplest equation:

Power = torque * rotational speed * 2PI (ignoring units) or

Power = Torque * RPM

pretty simple!

So obviously power is a function of torque. It is the function of the transmission to "do the right thing" and keep things at the high torque portion of the engine to get the right power to the wheels. If you look at the torque and power bands of the TFSI and the TDI engines things should be pretty obvious how all this depends on RPM of course and how these 2 engines differ and how the 0-60 accelerations are virtually identical even though the TDI has higher torque (428 lb-ft) and lower power (240hp) and the TFSI has higher power (310hp) and lower torque (325lb-ft).
(I do not read physics forums but I did pass 8.01)

Originally Posted by mirin S6

This is where you are wrong. For all out acceleration, the transmission's job is to keep the engine at max power, not torque. The "right power to the wheels" is peak HP. I have an S6 which has a pretty broad torque band. It has 400+ foot-pounds between 2,000 and 5,000 rpm. For max acceleration the transmission will keep the RPMs up high near peak HP, even though torque begins to fall after 5,000 rpm. You will not get the same acceleration if you manually shift between 2,000 and 5,000 rpm, even though you are at peak torque. You will notice the same thing in your car.

I'm not trying to downplay the TDI. I bought the S6 in early 2013 before the TDI was available in the US. If it were available, then I would have strongly considered it and saved a few bucks. I'm sure the cars feel pretty much the same under moderate acceleration (2,000-4,000 RPM) because the torque and HP numbers are similar at low to mid engine speeds.

Originally Posted by mirin S6

This is where you are wrong. For all out acceleration, the transmission's job is to keep the engine at max power, not torque. The "right power to the wheels" is peak HP. I have an S6 which has a pretty broad torque band. It has 400+ foot-pounds between 2,000 and 5,000 rpm. For max acceleration the transmission will keep the RPMs up high near peak HP, even though torque begins to fall after 5,000 rpm. You will not get the same acceleration if you manually shift between 2,000 and 5,000 rpm, even though you are at peak torque. You will notice the same thing in your car.

I'm not trying to downplay the TDI. I bought the S6 in early 2013 before the TDI was available in the US. If it were available, then I would have strongly considered it and saved a few bucks. I'm sure the cars feel pretty much the same under moderate acceleration (2,000-4,000 RPM) because the torque and HP numbers are similar at low to mid engine speeds.

Originally Posted by in2dwww

Not quite. Power is needed to fight resistance. Torque is needed reach maximum rpm in a vacuum. Go ask a dentist how fast his drill can spin. 35k rpm will probably be the answer. The drill doesn't need hp to reach that speed. It needs hp to eliminate getting bogged down while drilling your tooth. The torque in the drill will take it up to 35k and the more toque, the faster it will reach that peak. Without horsepower, the drill would grind to a halt from 35k rpm the moment it touches your tooth.

The transmission will be shifting gears at the point that it's programmed to shift. This mapping can be done to compensate for load/resistance or it can be done for efficiency (torque and low rpms).

Originally Posted by mirin S6

This is where you are wrong. For all out acceleration, the transmission's job is to keep the engine at max power, not torque.

Originally Posted by feralc

I am not sold with Diesel engines, I like the performance of the gas engine, in Europe gas is so expensive that the Diesel engines makes more sense, but in the United States/Mexico where I live the gas prices are not that expensive, I do not like the sound of the Diesel engine and the lack of performance, even if the torque is higher, that will make more sense in a Q7 if I would be hauling something, not the case in an A6/A7
I tested Q7 models side by side and I preferred the gas over diesel.
The 3.0 tfsi is really good engine, the consumption is very good, and if I wanted better economy. I would have purchased a hybrid or an electric.
Nobody buys a sports car like a Ferrari based on economy, I know these are not Ferraris but I like my cars to perform, and if I need to pay a little more I do not care.

I read this test today and it is pretty impressive what Diesel engines are doing nowadays, but for saving $72.57 for a 1184 mile trip, getting there 43 minutes later and sacrificing acceleration (6.5 vs 8.1 0-62mph) and top speed (155 mph vs 142 mph advertised) and losing 36 hp for gaining 22 ftlbs, is in my book not worth it.

http://www.roadandtrack.com/car-revi...treaks-roa0214