[Grovsnus]

On the 35i, my experience is that DS is more for showoff than performance. It drags each gear out way above what gives max torque, which might sound aggressive, but isn't optimal. At least not for the N55.

As for keeping ECO PRO on, doesn't that also delay the throttle response?

For sporty driving, I turn off DTC+DSC.
After it several times prevented me from accelerating while coasting (to pass), and completely nixed my order to speed up, I gave up on it. With high performance summer tires on a dry road, there is no reason why I shouldn't be allowed to accelerate from 40. And even less reason why it then nixes the gas for several seconds while blinking the yellow nana-nana-boo-boo light.

I hope this can be fixed by programming, but as it is, it's downright dangerous. What if you go into the oncoming lane before hitting the gas, getting no response at all, and meanwhile the rest of the line behind you moves up and takes your spot, so you can't get back?
Or you give a quick steering correction to get the rear pointed at the optimal angle for exiting a curve? In that case, the interference can cause you to slam into the auto rail.

Anyhow, for me, sporty is with DTC+DSC off, using the paddles to assist, e.g. with engine braking or matching the gear to an oncoming curve. DS is near useless except for impressing the unwashed masses with loud sound, but that might be different on the N20.

Oh, and some hints for saving gas:
Keep the rpm low. Try to never exceed 1500.
If you can build up a little speed (at low rpm) before hitting a small hill, do so, so you can coast up and over it at under 1500 rpm.
Avoid full stops. If you come towards a red light, it's better to brake hard early and coast at low speed towards it than to gently stop and then start again.
But most of all, pay attention to others. If you turn onto a busy road, floor it to match the traffic speed as quickly as possible, despite it costing you gas. If you don't, you cost everyone who have to brake gas, and what goes around, comes around.