Lots of people do not comprehend what E46 refers to. Understanding of what a chassis code will likely to be the first step in grasping the nomenclature E46. BMW started labeling their versions using an E
designation in 1968 beginning with the E3 and E9. The sedan was the E3 and the 2-door was the E9 BMW uses this term to reference the new models. Sometimes these versions span several years but essentially are the same car.
BMW will design the identical car for a few years with only minor changes. This enables identical parts to fits many years to save costs. Look at the E46 for instance. Production began in 1998 with the sedan model and 1999 as the coupe model. In 2005 manufacturing for the 4-door ended however the M3 and 2-doors lasted until 2006. Nearly all BMW 3-series from 98-05, 80% of all components are the same.
With the exception of the different motors and the distinctive components that complement them, the E46 shares many other typical parts. The suspension however is practically identical from 1998-2006 with some exclusions of course. Those being the sport package suspension and the M3 suspension. Apart from the M3 or sport package, 70% of the total 3-series produced from 1998-2005 has truly exchangeable suspension. The exact same arms and bushings and the same struts and shocks.
This carries true to options such as the ac and heater, entertainment, lighting and other options. The AC expansion valve is identical on a 1998 328i which it is on a 2006 M3. This goes for the hood shocks and washer pump. The body components also share these character. Other than the coupes and M3, all sedans share identical doors, fenders, trunk and hood. The bumpers have been revised gradually to give a little difference from year upon year.
Computer systems and safety parts stay the same throughout the E46's Several components of the ABS system and airbag computer system have stayed the same through out production of the E46 even while many have received upgrades in the past. It is usually vital to upgrade or re-design an component due to a mistake or design problem. This is known as superceding.
Superseding components is a good idea when it has an excessive failure rate. One prime example is the power steering pumps. A good number of problems have caused the engineers at BMW to revise it about ten times. The first versions were too light to manage the expectations of the power steering unit and could get too hot because of lack of fluid transferred around the internal fin. Plenty of parts, like the E46 M3 center support bearing have not been revised.
Cooling parts are probably the normally repaired parts. The water pumps and thermostats fail at a fairly increased rate. Elements such as the expansion reservoir and radiator are made from an ABS plastic that has a tendency to get brittle over time. Apart from the cooling system, the BMW E46 from 98-05 is possibly one of the most reliable BMW's. Sales numbers verify the BMW E46 the most winning BMW ever.