BMW
12
on the E24.
When 'X' is capitalized and supersedes the series number (e.g. X3, X5, etc.) it identifies the vehicle as one of BMW's Sports Activity Vehicles (SAV), their brand of crossovers, featuring BMW's xDrive. The second number in the 'X' series denotes the platform that it is based upon, for instance the X5 is derived from the 5 Series. Unlike BMW cars, the SAV's main badge does not denote engine size, the engine is instead indicated on side badges.
The 'Z' identifies the vehicle as a two seat roadster (e.g. Z1, Z3, Z4, etc.). 'M' variants of 'Z' models have the 'M' as a suffix or prefix, depending on country of sale (e.g. 'Z4 M' is 'M Roadster' in Canada).
Previous X & Z vehicles had 'i' or 'si' following the engine displacement number (denoted in liters). BMW is now
globally standardizing this nomenclature on X & Z vehicles by using 'sDrive' or 'xDrive' (simply meaning rear or all wheel drive, respectively) followed by two numbers which vaguely represent the vehicle's engine (e.g. Z4 sDrive35i is a rear wheel drive Z4 roadster with a 3.0 L twin-turbo fuel-injected engine).
BMW last used the 's' for the E36 325is, which ceased production in 1995. However, the 's' nomenclature was revied on the 2011 model year BMW 335is and BMW Z4 sDrive35is. The 335is is a sport-tuned trim with more performance and an optional dual clutch transmission that slots between the regular 335i and top-of-the-line M3.
The 'M' – for Motorsport – identifies the vehicle as a high-performance model of a particular series (e.g. M3, M5, M6, etc.). For example, the M6 is the highest performing vehicle in the 6 Series lineup. Although 'M' cars should be separated into their respective series platforms, it is very common to see 'M' cars grouped together as its own lineup on the official BMW website. The M versions of the Sports Activity Vehicles, such as the BMW X5 M, could not follow the regular naming convention since MX5 was used for Mazda's MX-5 Miata.
Exceptions
There are exceptions to the numbering nomenclature.
For instance in the 2008 model year, the 125i/128i, 328i, and 528i all had 3.0 naturally aspirated engines, not a 2,500 cc or 2,800 cc engine as the series designation number would lead