3.0 TDI A5: Low RPM Power Issues?

Hello,

I'm planning to buy an A5 3.0 TDI and I test drove one yesterday. I really liked it, but one thing was a bit surprising: The car felt quite sluggish below 2,000-2,500 RPM, but then it had a strong surge of power above that. Shouldn't the car be pulling strongly already at around 1,500 RPM, at least according to the torque curve?

If this behavior is not normal, what could be the cause? (I know, it's like looking into a crystal ball... but maybe there are some common issues with the 3.0 version).

BTW: Does the engine actually have an oil quality sensor, or does it calculate the oil change interval based on temperature, load, starts, etc.?

Thank you.
Best regards.
Stefan.