Balancing Game Modes For A Racing Game

Hi there,

An associate of mine is making a Racing Game.

It is a Racing/RPG hybrid game and as such has things like dialogue, levelling up systems for characters, abilities that can be used during races and exploration modes etc and most importantly, classes for both characters and cars.

The classes for cars in this game are Tuner (JDM/Euro Tuners such as Toyota, Honda, Nissan, Mazda etc), Muscle (cars such as the Ford Mustang, Chevrolet Camaro, Dodge Challenger, Pontiac GTO etc) and Exotic (German/Italian/British brands such as Porsche, Ferrari, McLaren, Mercedes-Benz etc.) Each class has their own Origin story, part of the map, companions, unique parts in upgrades shops etc as well as having two race types specific to and only accessible to their class, and they are :

Tuner

Drift- The player must slide around a course for several laps, scoring as many points as possible and before the timer runs out.

Touge - A form of Japanese street racing in which two drivers follow each other down a mountain at speed, trying to stay as close to the other as possible.

Muscle

Drag - A sprint race in manual transmission. They are extended in this game and will have some corners/twists to do so.

Highway Battle - Two racers attempt to overtake each other by passing a minimum amount of traffic vehicles. The racer who has passed a minimum amount and kept the lead for at least 10 seconds wins.

Exotic

Speed Challenge - A series of speed cameras are plotted along a course. The player must drive through the cameras as fast as possible to get an overall top speed. The racer with the highest top speed at the end wins.

Eliminator - A timer is set to a circuit race - The racer in last place at the end of the timer is eliminated from the race.

I'm wondering how, as the game progresses, these races can be made more difficult or can keep up with the player's abilities as the game progresses? Or how they can counter exploits like being overpowered etc.