solidworks flow simulation accuracy

Hello

I am currently trying to use the solidworks flow simulation to calculate the drag and drag coefficient of a car, but first i am using a sphere to see if I have my settings correct. I am using a 100 mm diameter sphere with air velocity of 1.5 m/s, this gives a reynolds number of approximatelly 10000. in the tables this gives an answer of 0.5 to the drag coefficient and 0.005 to the drag force. The problem I have is how can I increase the accuracy of the simulation without increasing the solving time? currently I have a 1000000 fluid cells and 100000 partial cells.

if i use the automatic values of mesh i get an error of 50% which is too big