I am truly saddened by the ignorance of BMW history on this site. A BMW is not a car like a Honda or a Ford. It is a dedication to "form follows function" or "engineering first". It is a great automotive history that put to shame many, many brands for the last 40 years. Only recently have they caught up. Sadly, the modern vehicle is in the luxury wars. That is why I got out of my 2002 540i and into a Ti (or 2). Now for the history lesson from someone who has owned more than 20 BMWs in just about every series and body style from a 1968 1600 to the aforementioned 2002 540 (with a 4.4 liter engine).
All the numbers and letters once had a meaning.
"i" means injected. It is a little silly today when everything is, but mattered in the early 70's when most cars were carburated.
"T" or "t" means Touring which in Urp = station wagon. Yes our little hatchbacks are not station wagons but have the rear hatch as did the 2002 Tourings (which by the way were denoted as "Touring" see picture in previous post, not "ti")
"ti" means "twin induction". In the late 60's/early 70's BMW upped the performance with dual carbs, each serving two cylinders. It was possible to get a "Touring ti" (perhaps they all were) however, you could get "ti" on coupes and even 4 door 2000 sedans (never formally imported)
"tii" is simply the combination of the two designations so "twin inducted, injected" 2002tii were made from about 69 or so through 74. And yes it was Kugelfischer (sp) mechanical injection. The injection pump came off a tractor! (By the way, if you ever buy one of these wonderful wonderful cars, make sure that pump is in good shape. Rebuilding or replacing it can cost a fortune)
Now onto the rest of the numbers/letters.
Early on, BMW numbering was backward to today. At that time, a 2002 was "20" for a 2 liter engine and "02" for 2 doors, thus the 1602 and 1802. There were also some word names such as the Bavaria which was renamed in 74 or 75 to the 3.0 Si. The counterpart to this was the glorious 3.0 CS coupe (of which there were also 2800 CS models) Again the numbers denoting the engine size.
The 2002 was replaced by the 3 series in 77
An all new 5 series was introduced to the US in 75
The Bavaria/3.0 S was replaced by the 7 series in 77
The CS was replaced by the 6 series (not sure what year)
From then on, the 1st number denoted the series and the last two told the engine size (or approximate engine size) until marketing got involved.
The 320i was sold from 77 thru 83 (what a piece of *&^%). However BMW got rid of the bad motor/injection setup in 81 and it actually was a 1.8 liter from then on. They did not have the balls to call it that until they brought out the new body style in 84 at which time it became the 318. Also offered was the 325. It was offered in "i" form and "e" form and some that had neither designation. The "i" had the traditional high revving engine (6400 redline I believe), while the "e" (eta is correct, supposedly meaning economy) had only about a 4600 rpm redline. Here is the first time marketing reared its head. The "eta" is actually a 2.7 liter engine. However, since it was the downmarket model, BMW didn't want it to sound like it was better, so rather than being the 327 that it should have been, it became the 325e. From there on the 3 series did stay somewhat true to form. There was a true 323 sold in Europe in the early 80s that some people gray-marketed over here. However, as stated earlier the 323 of the late 90s/early 00s was a 2.5 liter engine. Why? Because the 325 had just become a 328 and they wanted more marketing distance between it and the lower end model. I also think that there was a time when you could buy a 330 and a 528 and they both had the same engine. Nice, huh?
From there all hell breaks loose and the designations become inconsistent year to year.
At times "S" meant Sport. Other times, it just designated a coupe.
The iX of late 80's 325 became Xi when BMW brought 4-wheel drive back.
I own a 92 325iC (C on the title, not on the trunk). It is a convertible. Later they did use C on the trunk for Coupe because Lord knows we can't count doors.
Other series seemed a little more true to their designations. When BMW redid the engine for the 5-series in 79, they changed the designation from 530 to 528. However, the 530 had a bad reputation for cracking heads due to lousy emissions design, so that could have played a role. As it progressed, it became a 533, a 535, a 530 and a 540, all correct designations until 2002 when they popped the engine to 4.4 liters. Nowadays, they don't seem to want to change a designation until the body changes, or they introduce an alternative engine option. I believe the 545 is running the same 4.4, but am not sure. Maybe 545 just sounds better than 544?
Side note: I find it odd that in the 90s I could buy a 3.0 liter V8 and now I can buy a 3.0 liter straight six. Why the change? From all I've heard, once the block problems were straightened out, the V8 was a good engine.
Anything said about the 5 series engines is fairly accurate for the 6-series and 7-series as well.
So amidst all this, I can live with a 1.9 liter engine in my 318Ti.
One more (obscure) note: while "L" was/is used to designate a 7-series long-wheelbase model (4 inches longer, all in the backseat); there were some rare "L" models of the 7 series (and maybe 6ers as well) in the 80s. Back then it stood for "Luxury", though some thought it meant Leather because every conceivable surface was covered in it.
Think about this: In 1968, how many American cars could you buy with an Overhead cam engine, disc brakes and fully independent suspension. I'm not 100%, but I believe none. However you had all those things in a little 2002 (or even 1602). That is what your Ti represents: a history of great engineering, not just a car. Learn your heritage. It makes the ride that much sweeter.