Skoda Octavia 1.5 tsi DSG mhev style. 

 

When driving in D I want to have stop-start disabled during traffic jams - it's very annoying to have the engine stopped and started when moving an inch forward.

 

Now if I am pressing SET button, and disable the stop-start, the car is supposed to maintain the idle RPM and never cut off the engine, right?

Mine basically stops the engine (rpms go to 0, engine gets stopped for a sec) and starts back the engine automatically, without the driver's intervention. However I, personally, don't see this as a normal behavior. The single way to have the engine running all thr time, is to switch to SS. 

 

Is this the expected behavior on MHEV? Or is it a bug within the software? 

 

 

In a not MHEV car and with the start/stop system disabled the engine never stops. I'm not sure about a MHEV car although I find it strange that it would work like you described.