Drag:
Viper
903HP
0.72KG/HP
Fastest 1/4 mile 7.88 secs
Fastest 1/2 mile 11.98 secs

im working on getting two cars for each race mode so here is what i have so far:
Grip: Mitsubishi Lancer Evolution; 852bhp
Drift: Mazda RX-8; 774bhp
Drag: Shelby GT500; 739bhp
2 Speed cars: Pontiac GTO; 855bhp Ford GT; 936bhp

i will update this as soon as i get 3 more cars for the remaining race modes

I owned ryo lol I try at everything cept the first speed everything else was easy

it may look easy but its actually difficult. u need the right cars, what cars did u use
against ryo and how much horsepower did they have?

drag:Lambo merculago lp640 (i got 1127bhp)
drift:Pontiac GTO
grip:use this cheat and then tune up (cheat:mitsubishigofar)
speed:Dodge viper srt10 (hard to handle but you get use to it in end)

use Toyota Supra n tune it to the max get it right n it will do 1/4 mile drag in 7 secs

I use the GT 500 in drag runs 6.50 with 712 bhp

Drag: GT500; 740bhp
dont know about the second car
Grip: Evo; 1016bhp
Mazda speed 3; 625bhp
Speed: Viper SRT10; 753bhp
GTO; 855bhp
Drift: GTO; 665bhp
RX-8; 949bhp

drag: charger rt 974bhp
drift: camaro ss 886bhp
speed: evo ix 1,012bhp
grip: evo 1,016bhp

grip:nissan gtr[r35]
drift: pontiac gto
drag: pagani zonda f
speed:evolution

the evo is better for grip
gto for drag
zonda f for speed
drift is rx7

I found the dodge challenger was way way better than every thing for drag if you have all
stage 4 parts plus you don't need nos I used this and became the drag king in 2 hours and
for drag don't waste money on brakes you don't use them
the Nissan silvia (s15)for drift all stage 4 parts
the bmw m3 e42 for grip all stage 4 parts
still working on speed I hope this helps.

Every thing I said then and for speed of all things use the super promotion Nissan skyline
r34 pre tuned a bit of a hand full bet it works very well
keep all of the kings cars and use them to complete the game

i play nfs prostreet in ps2 and these are my best cars! they all tuned up to stage 4.

GRIP: Nissan GTR r35
DRAG: for straights, Shelby GT500 which 1/4 time = 6.8sec
1/2 time = about 10secs
for wheelie, Dodge Charger R/T = 1330+ft can you get in wheelies
DRIFT: Mazda RX7 and Nissan Silvia S15
SPEED: Ford GT (but harder to control in very tricky tracks)
Porsche 911 (it is easier to maneuver in tricky tracks and can make 248mph on speed
traps)