The fuel pressure in a smart is restricted by a regulator to 3.8bar. By up-rating the fuel pressure into the fuel rail, you can increase the amount of fuel going through the injectors for the same time frame.

After a bit of research we discovered that we could use a fuel pressure regulator from an Audi A6 which has a fuel pressure of 4bar with the same fitment as the smart.

Bosch part number: 0280 160 575

We have been running these on 2 cars since June 2006: a Brabus 101 Roadster and a highly modded fortwo, and both demonstrate a notable improvement in the mid-range power (essentially overtaking power) and firmer under acceleration.

The fuel pressure regulator is located at the end of the fuel rail next to the throttle body.

Remove the big retaining clip by sliding it out the back of the fitting; you may need to lever it if it’s a bit tight.

Cut the cable tie to the vacuum hose, and pull off the regulator.

Pull out the original regulator. It may be fairly tight because of the o-ring seal.

Comparing side by side, you can see the Audi regulator has a larger central bore, and an additional fine filter for the fuel.

Use a small amount of silicone free oil to moisten the o-ring, and press the new regulator back into the housing. It may need a bit of pressure as the o-ring squashes into place.

Refit the retaining clip and the vacuum hose and secure with a cable tie.