basically i started with an s14, it sucked so i started again and bougt an evo, it was good for winning races and i made plenty of cash so i bought a r32, i sold my evo and then my 32 had barely any mods and couldn't win any races, i just scraped through doing some races against rubbish poeple i had missed...so i modded it a lot and it started winning races and i had plenty of cash, so i bought an rx7 and sold my 32. I'd made the same mistake twice. So guys, Never buy a new car unlless u have over 20k for modding it up to the spec of the car u were selling.
So...im starting again, what's the best car to start with?

The Evo as you said, it's pretty much the most bang for your buck. Just keep upgrading it, I also bought a R32 a little ways into the game, but I pulled through and tuned it up. Then, once I got the Wangan open, I got a R34 and did the rest from there. It does come down to having the right amount of money for tuning. So try to make sure you always have money left over for a Engine upgrade or something.

The Evo 3.
What I did was not modify it at all until I beat Blood Hound.*
Then once I beat Tailgunner, I did the mileage trick and modded it fully.
I took on Speed King next and won on the first try.
I then bought Speed King's car and did the same modding and stuff to beat White Charisma
I had 2 Wanderers left to beat (ZERO and Glamour Girl) before my PS2 died.
*Do not do this unless you are insane.