I have a feeling this has come up before, but…what do all these different initials mean on cars?
SE is Sports Edition
GT is Gran Tourismo
but my brain is too tired to come up with more.
Usually an “L” denotes luxury, which is an optimistic designation in most cases. Of course, just as often they pick some letters that sound good in combination.
The letters usually represent “trim levels”, or the standard equipment package that car gets. Sometimes this covers the engine, but usually engine capacity is seperately delineated (ie. BMW model names, where the last two digits represent the (rough) engine capacity in liters.)
A lower case “i” after any of the letters means the engine is fuel injected, but since almost every production engine is these days this one’s getting less common.
“C” often refers to convertible or cabriolet.
Sometimes the letters denote an actual model name (see below), but usually they’re chosen simply because they sound right together. “GL” almost always denotes a mid-level trim package, but the others can be a top-of-the-line package for one manufacturer, and the stripped version for another.
"R"s usually refer to a “racing” model, especially following a hyphen after some other combination of letters (SE-R, GT-R, GS-R, etc.).
NSX, as in the Honda (or Acura, Stateside) NSX was an abbreviation of “New Sportscar X”, the prototype’s working title, which just happened to stick.
MPV, as in Mazda MPV, stands for multipurpose vehicle. In the UK its the pejorative term (along with “people carrier”) for the vehicle class, like minivan is here.
As UncleBill noted, GT stands for Gran Tourismo, or Grand Touring, depending on where the car is built; SE can also stand for Special Edition. LE usually stands for Limited Edition for Euro-market cars, but in the US GM uses it as a trim level on Pontiacs (and I think its trademarked).
Very very occasionally, they’ll do something original, like Ford (except in Europe), which uses “Eddie Bauer” (God knows why, since I he doesn’t actually do anything to the cars) to denote its range-topper for most model lines.
Sometimes they mean something. Our Mitsubishi, for instance, sports the letters “GDI” on the trunk lid. Means “gasoline direct injection”, which in spite of its generic sound is the manufacturer’s term for a specific type of fuel injection.
Sometimes they just denote a specific variant of a car model without actually standing for anything. The flodmother’s old VW Golf was marked “SL”, which just meant “the one with air conditioning standard and lots of other nifty bells and whistles”.
And I can’t post here without mentioning the weirdest one of all: the fancier version of the Honda CR-V (cute ute), at least in Europe, is badged as the CR-VX. Just what the customer wants: a car named after a certain part of the female anatomy.
For the Mitsubishi cars that I’ve done the catalogues for, the letters (if there were any at all) went in this order:
GLX - luxury, most expensive
GLS - sport, mid-range, some luxury options, some options designed to make it look more “sporty”
GL - basic, no options
As I think we have concluded here, the acronyms mean whatever the manufacturer wants it to mean. Some more examples:
Buick GS-X (early 70’s): Grand-Sport eXperimental
70’s Volvos started with a DL, DeLuxe. Upscale models were GL, Grand Lux. Fuel Injected cars were GLE, Grand Lux Electronic (fuel injection).
The dead-bottom-of-the-line Toyota Corolla trim level is VE.
Very…Eh?
Interestingly, this is the letter scheme used for most of Volkswagen’s models.
I think they claimed it was “Value Edition”.
R usually stands for Racing, but Type R nearly always stands for Wannabe.
(If my sources tell me arightly, only about 500 of the original Type R racing-type car were made, all of them in Japan. People who like to “rice out” their cars are often fond of putting “Type R” stickers on them, regardless of the fact that they’re fooling exactly nobody who knows what a Type R actually is)
With General Motors cars, LE (Luxury Edition) is the standard vehicle. SE is the “Sports Edition.”
Usually the the differences are fairly minor, at least for an outside observer, but sometimes they’re substantial.
With the first-generation Saturns, the Saturn LE was the four-door sedan and the Saturn SE was the two-door coupe. (There were two variants of each: LE 1, LE 2, SE 1, and SE 2. The “2” version had more bells & whistles, while the “1” version was the stripped-down economy model.)
I’ve also seen an SL designation, which I presume is a hybrid of luxury and sportiness.
Mercedes partial list
S = Sport
SS = Sport Supercharged
SL = Sport Light (re: weight)
SLC = Sport Light Coupe
SLK = Sport Leicht Kurz (Sporty, Light & Short)
What about the designation SS? Supersport?
My memory bank just took me back to 1969, and my ‘69 Chevelle 396 SS (Supersport) 4 speed Muncie Trans, 350 HP. and, oh boy, did that car keep me in trouble with speeding tickets (if they could catch me on a given day.) 
Additional Mercedes data. With older Benzes, S stood for Super, and was an increase in power (dual vs. single carbs) and luxury above the standard number, which stood for engine displacement in litres. Add the E for ‘einsprintzer’ and you have an injected engine, as opposed to the carbureted base model. C could stand for coupe or convertible. L stood for long wheelbase in the sedan class, and light for the sport coupe class.
Early BMW I never did figure out. A 2002 was a 2 litre single carb engine. A 2002ti had dual sidedraft webers IIRC, and the 2002tii had fuel injection. Boy-o they went like greased cats, though! Little boxes would do 120+ and not bat an eye.
I’ve got a Dodge Daytona CS Turbo ('89). So it’s a something-or-other sport?
Is Volkswagen part of Daimler-Chrysler? That might explain the similarity, as D-C recently acquired a controlling interest in Mitsubishi.
And then there is the TT model.—
I only remember a TT designation a couple times. Seems like Toyota had that for maybe a year back in the 60’s or 70’s and then dropped it (for obvious reasons—who wants to drive a “tee tee” car? ----Not very macho) ------I guess the Japanese had witnessed the popularity of the American SS and ST models and foolishly thought that TT would work too.
But I recently saw TT on a newer Audi. What is TT supposed to stand for in these cases and why is Audi stupid enough to keep using it—at least on cars sold in America?
Ya’all missed RS - the Rally sport, this link I think says who came up with it to begin with?
http://hjem.get2net.dk/genie/XRFiles/rscossie.html
Then again, I only noticed this cause the Chevy camaro is an RS.