Peter - brakes do not drag and tires are inflated to spec (29psi Front/32psi Rear).

I know that the consumption in Sport mode should not be much different coz last month I drove the car one tank load in Sport mode and I got about 390km before the fuel warning light came on.

Plugs/wires changed 3 months ago which solved a misfiring issue.

I will check the exhaust now for black and sooty stuff...does a bad O2 sensor cause the car to run rich?

Benz300 - the E/S switch in my car is all there is to go by.There are no indications.

However, the car is still starting in 2nd gear coz I counted the gear changes.I have driven the car in Sport mode a couple of times before and I know the difference.1st gear on this car is short and it will accelerate quick and swiftly change to 2nd gear.Now it looks like there's more power coming from the 2nd gear start.

I wonder if a richer mixture causes this?

Keep it coming guys!