My Smart is using a lot of oil?

How much is a lot? It is using a lot when it's uses more than 1/2 a litre on 1000km (625mile) Then the engine is in a downward spiral. It’s Likely that the oil control rings are stocked in place allowing excess oil to enter the combustion chamber.  It will then consume more oil  and the compression on the cylinder will be less.

The next thing can be that an exhaust valve will burn away as the engine will be running extra hot when low on oil, causing the engine to go onto two cylinder. It will have no power and will sound strange.

If maintenance has been sporadic the next thing to go will be a spark plug, the electrode will overheat if the oil is to low or oil will cover the plug and cause an electrical short circuit increasing the risk pre ignition. This is why the correct oil and fuel and plugs are so important.

Why is the correct oil and fuel and plugs are so important?

A Oil 0w – 40w Fully Synthetic like Mobil 1 is recommended (We have tried other oils but the smart does not like them, it burns them differently and quickly!) Remember that the difference between the high and low on the dipstick is only 1/2 a litre, do not overfill it.

NB. The Smart turbocharged engine puts special requirements on fuel.  Turbochargers make more power, in doing so increase the temperatures the engine has to deal with.  High temperatures can cause pre ignition or knock, this is where the higher temperatures and increased combustion chamber pressures can cause the fuel to ignite prematurely and uncontrolled, if this happens it could burn out a valve almost instantly or indeed destroy a spark plug as detonation is uncontrolled explosions in the combustion chamber, these create many shock waves as the mixture spontaneously explodes putting the spark plug under immense pressures.  

Higher octane fuel RESISTS  premature exploding better so the engine can run closer to its limits for making decent power without having to ‘back off’ to preserve the engine. BRABUS models are meant to use only 98+ Ron fuel (indicated in the fuel filler flap) There are additional cleaning additives used in premium fuels but we do not  have test data to prove or disprove the usefulness in Smart applications.

NB Spark plugs must be changed as per the service schedule, failure to do so will could mean pre ignition (see above) or plug failure or destruction either of which could mean engine failure. The 600 & 700 cc engines have 6 spark plugs. A lot of non specialised garage's renew only 3 during the service.

I have a performance exhaust and my engine light has come on, is the exhaust faulty?

A No not necessarily, the smart car has set parameters for all the engines settings, by changing them from standard you run the risk of the engine management unit thinking there is a problem.  Changing any part of the car can cause this but exhausts and air filters are most common.  

NB. You can buy a lamda high temperature probe (part ext-1012-1) that fits between the exhaust and lambda sensor that alters the reading reducing the chance of the engine light coming on.