Morning Robert
Welcome to the Forum
The GO5 X6 as far as I am aware are all 6 cylinder Diesel or Petrol plus the Petrol V8 as far as I am aware the engine choices are
The xDrive40i M Sport has a 3.0-litre, in-line six turbo-petrol engine with a maximum outputs of 280kW and 540Nm.
The xDriveM60i has a 4.4-litre, eight-cylinder turbo-petrol engine with maximum outputs of 390kW and 750Nm.
The xDrive30d has a 3.0-litre, six-cylinder turbo-diesel engine with maximum outputs of 219kW and 650Nm.
The M Competition model has 4.4-litre, V8 turbo-petrol engine with maximum outputs of 460kW and 540Nm.
If it is a traffic light racer you want then the V8 is hard to beat but obviously operating costs are higher than a 6 cylinder petrol or diesel Fuel,Tyres, Insurance and servicing
I have 2 X5's a 4.6is V8 around 18mpg average but glorious noise and acceleration (High days and Holidays car now) and a daily driver 3.0d around 28 mpg around town high 30's on a run
Hope this helps
Dave