Engine choice
▶ There are almost too many engine choices to mention here. The N46 was the 2.0 Valvetronic unit fitted to the 127bhp 318i and the 148bhp 320i, with ECU and intake differences on the same engine.
These were replaced by the N43. This engine has a similar bottom-end, but a new head and pistons without Valvetronic, yet with direct high-pressure injection and Nox-sensing Lambda with electric water pump. These gave 143bhp and 170bhp in the 2007-onwards 318i and 320i.
The 325i and 330i were both all-alloy Valvetronic straight-sixes that gave 215bhp and 258bhp from 2.5- and 3.0-litre capacities respectively. These were replaced in 2007 by directinjection engines with 215bhp and 268bhp – now both 3.0 litres.
The N54 twin-turbo 335i pushed out 302bhp and the unit was retained into the LCI range in 2008, though replaced in late 2009 by the single-turbo N55 – which was more reliable and produced the same 300+bhp.
The early diesels were the good old M47N from the E46, producing 122bhp in the 318d and 163bhp in the 320d. These were replaced in 2007 by the N47, an all-new alloy block design with the rear-mounted timing chain. More efficient and a lot lighter, the N47 gave 140bhp as a 318d and 177bhp as a 320d – Efficient Dynamics models gave 163bhp.
The M57N 2.5d and 3.0d were alloy block units from the E60 5-Series, the final versions of the M57 that arrived in 1998. The 325d gave 194bhp, the 330d a very impressive 230bhp. The replacement N57 was a 3.0 unit with varying degrees of fuel and boost; the 325d delivered the same 194bhp and the new 330d churned out a whopping 240bhp.
The 335d gave 282bhp with the M57N engine and was only ever offered as an automatic.