The smart fortwo 451 ran from 2007 to 2014 and in those 7 years we saw a tightening of the emissions laws
in Europe which meant that 451 exhausts changed. Due to the confusion, it seems necessary to create
a visual list so people know what they need should they need to fit a replacement exhaust.

Any car created after September 2009 had to conform to Euro 5 emissions laws,
however, smart may have fitted Euro 5 exhausts before this time.

Euro 4 Non Turbo and Euro 4 Turbo

It was the same for both engines.



Euro 4 Non Turbo Brabus and Euro 4 Turbo Brabus

It was the same for both engines.



Euro 5 MHD

The non turbo model has a large silencer and a short pipe from the flexi-joint.



Euro 5 MHD Brabus

The non turbo model has a large silencer and a short pipe from the flexi-joint.



Euro 5 Turbo

The turbo model has a narrow silencer and a long pipe from the flexi-joint.



Euro 5 Turbo Brabus

The turbo model has a narrow silencer and a long pipe from the flexi-joint.



Euro 4 Diesel (45bhp)

I don't have a photo yet but it looks like the Euro 5 diesel exhaust but without the
pressure and temperature pipe connections coming out of the silencer can.

If you have a photo, please send it over.

Euro 5 Diesel (54bhp) With DPF

This version has 3 extra connections. 2 on the top and 1 on the left. These are for temperature and pressure sensors.



American Non Turbo

Thanks to Phil for the photo of the US exhaust.



It looks exactly the same as the MHD exhaust.

This would make sense as America have strict emissions laws (believe it or not. Ask VW).
So for our non turbo MHD to adopt their exhaust type seems to add up.