The first event with the FF car under 250 HP?
Easy thing. Mini Cooper S. Do some slight tuning, buy Soft Sports tires and you're done. The car is in the premium dealerships, you just buy the cheap performance mods (Oil change, ECU, Sports catalytic converter, Racing Filter) and beast the competition. The car will then be useful for the Mini challenge both in A and B spec 👍.
I love this little car, it's a rally champion. Believe me.
For the second event (4WD Car around 300HP) I used the same formula but with a Impreza WRX STI '10. Again, fantastic car to drive and good enough to beat the competition.
After clearing the second level Rallies you should get a gift ticket for a rally car, which you should use for the top level Rally.
Hope I helped.