for the rear cargo area, roller sun visors for rear and side windows. A "latent heat accumulator" was available as an option up until September 1999. The accumulator stores engine heat by converting a salt from solid to liquid form (phase transition). The insulated tank can store heat for several days. The next time the vehicle is started, this heat is automatically used to reduce exhaust emissions (by heating the engine up to operating temperature quicker), for cabin heating and window defrosting. Separate to the latent heat accumulator is the Residual Heat function (activated by a button labelled "REST"), which allows the demister and cabin heater to use the heat of an engine that has recently been turned off (using an electric pump to push hot coolant through the heater core). Engines Petrol engines At launch, the petrol engines consisted of the BMW M52 straight-6 engines and the BMW M62 V8 engines. In late 1998, the "technical update" (TÜ) versions of these engines were introduced, introducing double VANOS to the M52 and single VANOS to the M62, primarily to increase torque at low rpm. For the facelift of the model range in the year 2000, the M52 was replaced by the BMW M54 straight-6 engine and the version used in the 530i model topped the Ward's 10 Best Engines list in 2002 and 2003. The post-facelift V8 models (535i and 540i) continued to use the M62TÜ engine. Specifications for European models are shown below.,, Diesel engines The initial diesel models used the BMW M51 turbocharged straight-6 engine carried over from its predecessor. In 1998, its successor the BMW M57 was introduced in the 530d model, however the BMW M51 engine continued to be used for two more years in the 525td and 525tds models. In 1999, the M47 four-cylinder turbo-diesel was introduced in the 520d model, which is the only E39 model to use a four-cylinder engine. Specifications for European models are shown below.,, Drivetrain Manual transmissions Six-cylinder petrol models were fitted with either the 5-speed Getrag 250G or ZF 320Z (S5-32) transmission, depending on the year and model. Diesel models with the M51 engine were fitted with the 5-speed ZF 260Z transmission, while the M57 diesel models were fitted with the 5-speed ZF 390 (S5-39DZ) transmission. V8 petrol models were fitted with the 6-speed Getrag 420G transmission. Automatic transmissions Some pre-facelift six-cylinder petrol models were fitted with the 4-speed