Need help keeping up online

So I am not new to forza but I feel that forza 5 is different than any forza I’ve ever played but I can’t seem to find cars to keep up or out drive people online. I race b and c class and can’t find a car that will hang! I’ve tuned them the best and I can and would not like to use someone else’s tune because I can’t change the wheels or bodykit. Just wonder if someone could give me some tips on cars or anything that could help. I also drifted every night on forza 4. I only drifted rwd and it is near impossible on forza 5 it seem like just looking for all if any tips. Thanks