Coasting (or inertia mode) should be deactivated in S mode with the DQ381. I would form a habit of switching to S mode when ever you need it, it's simple enough to pull once on the shifter for S, and pull again back to D.
Disabling the function in D would require TCU programming - although I would consider leaving this eco function alone*
It can also coast in any engine mode; Eco, Comfort, Sport,
Cupra - where this can be confusing. Going into Sport or
Cupra engine modes then pulling the shifter back to D, activates coasting again.
The low rolling speed pickup issue (when pulling out of a junction - for want of a better description!) Is the most severe
problem with the default programming of the DQ381 across multiple manufacturers using it!
It's not
specifically a coasting issue - as applying the brakes once, takes the gearbox out of coasting. But the pickup delay is very similar in both scenarios, due to the intentionally smoothed clutch engagement in D.
While coasting, this delay is felt when applying throttle out of coasting. It also applies smoothing while rolling in 1st gear - resulting in the nasty pickup delay out of junctions.
*Ideally, a tuner could increase clutch engagement speed in 1st gear (copy paste the settings from S mode into D) as it is simply a programming choice by manufactures to make the DQ381 feel more like a torque convertor for the general public.
Another common solution is to disable 1st gear while rolling - only 1st gear is used from standing stops, but I would expect more turbo lag pulling from 5mph in 2nd gear, at least the response of acceleration is immediate, which would be preferable at of junctions imo.
Theoretically; there is also one more solution to the issue without any tuning and while being in D... Left-foot braking
(Never do this).
