Well as chief mechanic..you get to play around with the cars quite a bit.
These cars are a race machines....They are built to go fast .
You will have all the set ups available to you via the factory or you can make up your own.
You could play around and set it as you like using aerodynamics, suspension geometry springs damper settings and different grade tyres from soft to hard .

Once you get comfortable with the being able to drive the car around you get to change more settings .
Yer thats right more, you get to select shift points on the gear box the gear ratio that you run,
ride hights you want to run the car at, sway bars, shock damping hard -soft.
The F1's of model car racing also use 4WD, yep thats  right four wheel drive .
 

Then when you get that close trim tabs on the body shell help just that bit to fine tune the cars aerodynamics.
Like I said these things are like  the real F1 what ever you do to a full size car we do.

The managers choice hmmm,
 There are several classes of car available he's got to  choose from.

1/8th gas would be rated as F1 or Indy cars these are 3.5cc unrestricted spec 4WD 2.5Kg rockets

1/10th Gas 235mm and 200mm chassis,would be classed formula 3000.These are 1.7Kg rockets.