Grand Prix Story/Parts

Part Strategies
Almost all part strategies include engine and tires - the benefits are too compelling to miss out on these parts. Other parts clarify the racing style, which could be "slowly accelerate to very high top speed and stay there with very high handling" or "accelerate and decelerate very quickly so that avg. speed remains similar in all situations" or a mix somewhere in between.

Turbocharger/Supercharger + Carbon Brakes
This strategy trades off raw stat boosts for better in-race performance with acceleration and deceleration - which has the net effect of allowing you to stay closer to top speed for longer periods. This should be weighed against simply increasing Handling scores, which reduces needs for both braking and accelerating.

64-bit
A heavily aura'd 64-bit can push the bonus of a trained driver over 100 points for each stat(while most of the drivers will naturally top out around 50-60 points). Unlike the Big Wing or the high-tier Gears(which are natural alternatives), it's a balanced boost with no downsides.

Light Chassis/Carbon Chassis
The chassis primarily improves durability; however, if you invest auras in the Light Chassis you will also get a strong boost to Speed as well. This can make it a possible candidate even for the endgame, especially if you're using a Mach Car or Kairo Car and have a low natural durability.

High Grip Tires vs. Everything Else
The High Grips have the best Handling score of any tire, but they don't give any percentage bonus. This makes them a better candidate for cars that have low natural Handling and high Speed/Acceleration.