Are the later E53s more reliable?
 

The high-mileage discussions here made me wonder whether my 05 3.0 will suffer from the same problems that the older ones have. By 05 did BMW use better water pumps, window regulators, transmissions, etc?

Just thinking ahead, when my compfy warranty will end.

There is little data to support any supposition.

I would expect items like window regulators to continue to be problems, and miscellaneous electrical faults to increase slightly due to the increased complexity of the vehicles. Transmissions are different (6 speed) but there is simply no solid data yet.

Maybe I'm mistaken but I thought only the V8s got the ZF 6-speed auto, while the 6's stuck with the GM-sourced 5-speed auto. So the assumption is that whatever tranny problems cropped up before the facelift will also be there after the face lift, only if you got the 3.0 though.

You are correct that the 3.0 didn't get the 6 speed; I was speaking more generally about newer X5s, but you have to wait until the E70 to get a six speed with the 3.0.

Since different transmissions were used in different years, and different ones again between the 6 and 8 cylinder, even to the extent of being sourced from two different suppliers (GM and ZF), I wouldn't put it down to the transmissions but rather the related components such as the electronics control package and programming.

nature of the business in general would put the vehicle on a bell cure on reliability, with the middle years the most robust. of course this not include re-sourcing of parts to different suppliers. depending if the re-source / re-development is due to a quality issue or strategic - the OEM may know the resulting reliability, but it's a crap shoot for the public which part is better until field data becomes available.

initial launch of the vehicle will definitely have it's bugs - some parts will be over-engineered, while others under-engineered. you just can't simulate all real world conditions. as field data comes in, parts are improved to address these issues. over-engineered parts are then reviewed for PCO/cost saving ideas. typically, most of these should be sorted out after 3 years from launch, as part change can take over 2 years (time varies depending on severity). after this "peak" of reliability, the vehicle is continued to be reviewed for PCO/Cost saving ideas, where parts are reviewed for reduction in material/resourcing costs without "degredation" in quality. the level at which they carry out cost saving ideas depends on invested costs vs. planned return after implementation. however, when parts are re-engineered, reliability results are again unknown.

ultimately - not including changes in suppliers for strategic purposes, 4-5 years is typically the best in reliability, closely followed by the 6+year models, then from 3 to 1 year models. mid cycle changes also bring in more chance for issues, so part reliability depends on if it was updated or not.

YES! especially in cold weather