So that means (as of this year)..
SS- Z06 (C5) or C6 Corvette, or Lotus Elise
AS- C4 Corvette or Honda S2000, or Porsche Boxter
BS- BMW M3 or Honda S2000
CS- Toyota MR2 Spyder or Miata
DS- BMW 330Ci Sport, Integra Type-R, WRX?
ES- Toyota MR2, Miata
FS- Mustang Mach-1
GS- Toyota Celica GT (not GT-S), 05+ MINI Cooper S
HS- MINI Cooper
ASP- Corvetts
BSP- Corvette
CSP- Miata or Toyota MR2 Spyder, early CRX
DSP- BMW 3-series, Toyota IS300
ESP- Mustang or Camaro/Firebird
FSP- early Golf, Scirocco, Suzuki Swift GTi
STS- early Honda Civic Si, Subaru 2.5RS
STX- WRX, BMW 3-Series/M3 (E30)
STU- WRX STi, Evo, BMW M3 (E36)
SM- Whatever you got!
SM2- Mazda RX-7 TT, Corvette
AP- Mazda RX-7 Turbo
BP- Mazda RX-7 Turbo
CP- Mustang or GM F-Body
DP- early CRX, Miata
EP- Miata, RX-7 12A
FP- misc British roadsters, RX-7
FM- Formula 500
FSAE- Formula SAE
F125- Something Honda
That's all I've got off the top of my head based on National results from the last couple seasons. If you're going to start out with something and have the $$ and drive, at least start in the right direction...you may not be able to afford a National Setup, but just having the right car takes a lot of the work out of it.
The Paseo in HS would be perfect; its light and has 14" wheels and a willing motor. Get it aligned and decent tires and just drive it a lot, don't worry about too much else than your driving for now....except for some good oil of course!
-JamesW