RL stands for Road Luxury.
TL stands for Touring Luxury or something like that.
DB9 stands for the owner of Aston Martin followed by the model's generation number. Like Corvettes C5 etc.
Audi uses a similar system to BMW. A platform letter followed by a trim number. TT stands for tourist trophy.
CTS - C-series Touring Sedan.
DTS - DeVille Touring Sedan.
STS - Seville Touring Sedan.
XLR - Luxury Roadster. Not sure what the X means. V indicates supercharged.
GT means the car is in some fashion used in racing by the production company. Gran Turismo or Grand Touring.
HHR - Heritage High Roof.
300 - Ripped from old school chryslers that were built with 300 hp engines. Letters indicate trim.
SRT - Street and Racing Technology followed by the number of cylinders. (SRT4 for Neons, SRT10 for Vipers, etc.)
F430 - Ferrari through the F on there. 430 is displacement of the engine or a single cylinder.
Five Hundred - Ripped from Fairlanes which indicated trim level.
GT - Granding Touring (Gran Turismo)
S2000 - S is a roadster series Honda has produced. 2000 represents generation.
G35 - Platform letter and the engine used (VQ35 series). Same pattern for other Infiniti vehicles.
Jaguar uses S and K to designated platform. Second letter trim. R supercharged.
LS - Luxary Sedan.
Maybach names cars by their length.
RX-# - R stands for rotary. Used to be an option on old mazda vehicles. Not sure what the number stands for since they use another way to indicate generation.
Mazda3/6 are derived from 323 and 626. Not sure what spurred those numbers, but mazda exported those 2 vehicles under a different name to different countries.
Mercedes' system uses letters which indicate price. Additional letters are codes for extra goodies.
350Z - Z car. 350 is from displacement. 350 - 3.5L, 240ZX - 2.4L, 260Z - 2.6L, etc.
G6 - 6th generation Grand Am
In GTO, the O is Italian or something that means approved. Pontiac actually ripped that off from Ferrari.
S7 - Don't quote me, but I believe 7 indicates prototype number before settling on a production model.
tC - toyota celica
Volvo has used numbers ever since its DAF days. Its new naming system is a bastardized version of its old 3 number system which indicated size, engine size, doors.
Type R just indicates race trim.
That was all for fun. Some I have no idea about. This type of naming system was around before cars actually got names. Ford Model-T. Ford Model-48. Ford GT-40 (40 was its height). Chevrolet's first cars were just the production number minus a digit - 150 and 210. Plymouth used names like special deluxe coupe. Alot of cars badged under different manufacturers after being imported seem to get stuck with a letter/number name like the Fairlady-350Z and Skyline-G35. Toyota Supra is going to be tagged with a letter designation under Lexus soon (LF-A).
We can be thankful for having an aviation nerd as one of the designers for the Mustang since he suggested the name after a Mustang fighter plane he fancied.
Cars make names for themselves. Some guys would rather have a plain jane sounding '57 chevy than a race sounding S360Z Type R GTX or Barbaro or Funny Cide or Street Sense or Giacomo or whatever else sounds fast.