Title says it all.
Living in Europe corresponds to high gas prices, so i was wondering if an ECU remapping might save some money in the long term. Also… are there any negative impacts on the engine or other parts that should be put in consideration?
Nope
Automakers spend tens of millions tweaking the code in the ECU, no amateur tuner has any special magic sauce to defy the laws of physics.
Keep in mind that tampering with emissions equipment voids warranty and typically violates air pollution regulations (it does here in the US).
Factory tunes need to compile with emissions regulations so with custom tune which doesn’t compile with them you might save some amount of fuel. Basically it’s illegal but there isn’t really a way to test for example NOx easily, that’s why it took so long to catch vw with dieselgate.
long term, friend of mine wants to weld on some more metal to the camshafts of 1.9L TDI engines, to keep the intake valve open longer so some of the intake air is blown back out. you then modify the pistons, or the heads, to get the compression ratio back up higher. essentially making an Atkinson cycle diesel engine.
there are many other efficiency improvements to start with before remapping the engine, unless you have a truck and people have already provided better off the shelf solutions. its not nearly as easy as it sounds.
my 2017 chevy spark dumps fuel down the intake when engine braking down a hill. i presume they do that to keep the catalytic converter warm.
if your car does that, what you may be able to do is wire in a manual kill switch for the injectors.