The E38 730d

The BMW E38 730d, introduced in 1998, was the first diesel-powered model in BMW's flagship 7 Series lineup to feature a common-rail direct injection system, setting it apart as a more modern and efficient diesel option.

Engine Overview

The BMW E38 730d is powered by the M57D30 engine, a 3.0-liter inline-six (I6) turbodiesel. This engine marked a new era for BMW diesels, introducing common-rail direct injection, which greatly improved fuel efficiency and power delivery compared to older diesel engines. The M57 was renowned for its robust construction, power delivery, and a more quiet idle, providing a significant upgrade over the earlier M51 engine found in models like the 725tds.

Performance

The 730d E38 was in fact equipped with two different engines, depending of the year of production.

1998 - mid 2000's, the 730d delivered 184 horsepower (135 kW) at 4,000 rpm and 410 Nm of torque (302.4 lb-ft) @ 2000 rpm. The engine's torque delivery at low revs made it ideal for effortless highway cruising and provided a quite good acceleration even in a car as large as the E38 7 Series. For EU readers, as of the emissions, this was a certified Euro 2 engine.

Power Output: 184 hp (135 kW) at 4,000 rpm
Torque: 410 Nm (302.6 lb-ft) at 2000 rpm
0-100 km/h (0-62 mph) Acceleration: 9.2 seconds
Top Speed: 220 km/h (136.7 mph)

Late 2000's - 27th July 2001 (end of production), power was bumped from 184hp (135 kW) to 193hp (144kW), and the overall emissions were improved (for EU readers, M57D30 was now classified as an Euro 3 engine).

Power Output: 193hp (144 kW) @ 4,000 rpm
Torque: 430 Nm (317.15 lb-ft) @ 2000 rpm
0-100 km/h (0-62 mph): 8.9 seconds
Top Speed: 220 km/h (136.7 mph)

Regarding the reliability, the M57D30 was (and it still is) an unbelievably robust engine, but not bulletproof. There are no truly fragile components, but as any older engine without proper maintenance, it can fail. In case any repair is needed, the fact that it was widely equipped across many BMW platforms makes finding spare parts easier than ever. This also applies for any engine upgrades/mods you plan on doing.

While many owners might be tempted to do some power-oriented modifications, keep in mind that the gearbox used in the 730d - a ZF 5HP24 5-speed automatic (regardless of the year of production)- was not made for handling much more torque. Originally made for the E38 V8's, it was then paired with the later developed 730d (production starting from 1999), and was certainly not designed for handling anything above 450Nm (331.9 lb-ft). No manual gearbox was available on the 730d, so you will probably want to settle with stock power, unless you don't mind swapping another gearbox in.

However, the engine itself easily handles more power. In EU, it is the go-to diesel engine in terms of 'in-house' substantial power modifications, as some owners have reportedly increased their M57D30's power to over 400hp(298.2 kW).

730d Sound

730d Acceleration

Fuel Consumption

One of the standout features of the BMW E38 730d is its excellent fuel efficiency-performance ratio, thanks to the introduction of common-rail direct injection, allowing for more precise control of fuel delivery, resulting in better fuel economy without sacrificing performance.

Fuel Consumption (combined): 7-8 liters/100 kilometers (around 35-40 mpg)
Fuel Tank Capacity: 85 liters (22.5 gallons)

For a large luxury sedan, these fuel economy figures were impressive, making the 730d E38 a popular choice for drivers looking for a balance of performance and efficiency, especially for long-distance or frequent driving.

Given its quite generous power output, good torque, excellent fuel consumption and the lack of reliability issues, enthusiasts consider the 730d as the best diesel alternative the E38 chassis offers. While for most users this is generally true, neither the 725tds nor the 740d cannot be ruled out of question. The 725tds is the only diesel powertrain that also comes with a manual tramsission, and the 740d's unique V8 biturbo diesel feeling is something to take into consideration.