![[TW]Fox](/data/man-of-honor/2009.png){kind=avatar}
Emissions are almost directly proportional to fuel used. So, if you've found a magic way to increase fuel economy and performance without degrading engine longevity you've almost certainly found a way to reduce emissions, too.
Car companies spend significant sums of money on getting exactly the right blend of performance, economy and emissions from an engine. Some of the reasons trotted out for why remapping is amazing do not stand up to scrutinity.
'Oh yea its because in the rest of the world they have fuel made from donkeys not our amazing fuel' - car companies can and do vary both engines supplied and engine variants on a national market basis. BMW fitted an entirely different engine to the 330i in the North American market rather than the one found in the EU market for just this reason.
'Its because of the nasty EU strangling everything for emissions' - but people claim remaps give you amazing fuel economy, which would be beneficial for emissions.
The reason why vehicle manufacturers do not ship cars in banzai-mega-lol-tune states is because they need the cars to provide reliable service for a reasonable period of time, which a remapped car may or may not do. Thats the reason.
The only exception to this really are situations where the manufacturer offers the same engine but across various levels of power at different points in the vehicle range. In this example the reason why the Generic Hatchback 2.0 TDI 130 can be remapped reasonably safely to 170bhp is because the same engine is also used in the Generic Hatchback 20 TDI 170 too, rather than because 130 was decided on as the best power output.
