BMW 530d vs 540i: Straight-Six Diesel or Petrol?
530d vs 540i is the six-cylinder G30 5 Series decision: two smooth 3.0-litre straight-sixes with very different characters. The 530d (B57 diesel) is the effortless-torque, long-distance economy pick; the 540i (B58 petrol) is the free-revving, refined, quicker-to-the-top-end choice. Both are Euro 6 ULEZ-compliant across the G30 generation (2017 to 2023), so this is a character-and-cost decision rather than a compliance one.
Quick verdict
530d if you cover big miles and want the best economy and the biggest wave of torque. 540i if you want petrol refinement, a keener top end, and you do not mind the higher fuel bill. The 530d's 620 Nm makes it the relaxed long-distance cruiser at 40 to 50 mpg; the 540i's B58 is smoother still at the top of the rev range and quicker outright, but returns nearer 28 to 36 mpg and costs more to fuel and insure. Both engines are strong, well-regarded units.
Side-by-side comparison
| Dimension | 530d | 540i | Notes |
|---|---|---|---|
| Engine | B57 3.0 straight-six turbo diesel | B58 3.0 straight-six turbo petrol | Both silky sixes; the split is diesel torque versus petrol revs. |
| Power / torque | 265 bhp / 620 Nm | 340 bhp / 450 Nm | The 530d has huge torque; the 540i has more outright power and revs harder. |
| 0-62 mph | Around 5.4 seconds | Around 4.8 to 5.1 seconds (xDrive quickest) | The 540i is the quicker car; the 530d is barely slower in-gear. |
| Real-world UK MPG | 40 to 50 mpg combined | 28 to 36 mpg combined | The 530d is the clear economy winner, especially on the motorway. |
| Refinement / character | Smooth and near-silent cruising; big low-end shove | Smoother at the top end; free-revving petrol zing | Both refined; petrol feels crisper high up, diesel more effortless low down. |
| Running items | DPF, EGR, AdBlue/SCR to maintain | No diesel emissions hardware; walnut blasting for intake carbon | Different maintenance profiles; neither is problematic when serviced. |
| Insurance group (UK) | Around 40 to 44 | Around 42 to 46 | The 540i sits slightly higher on insurance and fuel. |
| ULEZ compliance | Yes (Euro 6, all G30 builds) | Yes (Euro 6, all G30 builds) | Both compliant; not a differentiator on the G30. |
530d: deeper look
<p>The 530d (G30, 2017 to 2023) uses the B57 3.0-litre straight-six turbo diesel: 265 bhp and a huge 620 Nm of torque, giving 0-62 in around 5.4 seconds and effortless in-gear overtaking. It returns a real-world 40 to 50 mpg, far better than the petrol 540i, and is frequently specced as xDrive, which makes it the ideal all-weather long-distance cruiser. From the 2020 LCI most cars gained the 48V mild-hybrid system.</p><p>The B57 is regarded as one of the stronger modern performance diesels, and the 530d is a genuine high-mileage car when maintained. As with any modern diesel, prioritise full service history, regular oil changes, and healthy EGR, DPF and AdBlue/SCR systems, especially on cars that have done a lot of short journeys. For a buyer who covers big miles in comfort and cares about the fuel bill, the 530d is the rational six-cylinder choice.</p>
540i: deeper look
<p>The 540i (G30, 2017 to 2023) uses the B58 3.0-litre straight-six turbo petrol: 340 bhp, 450 Nm, and 0-62 in around 4.8 to 5.1 seconds with xDrive, making it the quicker car and one of BMW's finest modern engines (the same fundamental unit that powers the Toyota GR Supra). It revs more freely than the diesel and is exceptionally smooth at the top of the range, with none of the DPF, EGR or AdBlue hardware a diesel carries.</p><p>The price of that petrol refinement is at the pump: expect a real-world 28 to 36 mpg, meaningfully thirstier than the 530d, plus slightly higher insurance. The B58 shares the modular petrol service pattern (charge pipe, VANOS, water pump, and walnut blasting for intake-valve carbon on higher-mileage cars) and, like the diesel, gained 48V mild-hybrid from the 2020 LCI. For a buyer who prizes smoothness, revs and outright pace over economy, the 540i is the more special engine to live with.</p>
Decision logic
Start with annual mileage and what you want from the engine. If you cover high mileage and value economy and a big, relaxed slug of torque, the 530d wins: 40 to 50 mpg, 620 Nm, and an effortless motorway gait, ideally as an xDrive. If you do fewer miles, want petrol smoothness and a keener top end, and can absorb the higher fuel and insurance costs, the 540i is the more rewarding and quicker car. ULEZ is not a factor (both comply across the G30). If you tow or drive in poor weather, the 530d xDrive is the natural pick; if you want the best six-cylinder petrol experience in a 5 Series short of the M550i or M5, the 540i is the answer.
UK 2026 pricing comparison
| Scenario | 530d | 540i | Notes |
|---|---|---|---|
| 2018 M Sport, 70k miles | £18,000 to £24,000 (530d) | £20,000 to £26,000 (540i) | Petrol six carries a small premium at this age. |
| 530d xDrive vs 540i xDrive, 60k miles | £22,000 to £29,000 (530d xDrive) | £24,000 to £32,000 (540i xDrive) | All-weather six-cylinder cruisers; the 540i sits a little higher. |
| 2020 LCI MHEV M Sport, 45k miles | £27,000 to £34,000 (530d) | £29,000 to £36,000 (540i) | Post-LCI with 48V mild-hybrid and iDrive 7. |
| 2022 LCI M Sport, 30k miles | £33,000 to £40,000 (530d) | £34,000 to £42,000 (540i) | Freshest G30 sixes; strong residuals on both. |
| Touring (G31 estate) equivalent | £19,000 to £35,000 (530d Touring, by year) | 540i Touring rarer in the UK | The 530d Touring is the more common six-cylinder estate; 540i Touring is scarce. |
Recommendation by scenario
| Scenario | Pick | Why |
|---|---|---|
| High-mileage long-distance driver | 530d xDrive M Sport | 40 to 50 mpg and 620 Nm make the 530d the effortless, economical motorway six. xDrive adds all-weather security for big-mileage drivers. |
| Wants petrol refinement and revs | 540i M Sport | The B58 is smoother at the top end, free-revving and quicker outright, with no diesel emissions hardware. The pick if you value petrol character over economy. |
| Fewer miles, fuel cost secondary | 540i | If you do modest mileage, the 540i's higher fuel cost matters less, and you get the more special engine and slightly quicker car for a small price premium. |
| Regular tower or bad-weather driver | 530d xDrive | 620 Nm and all-wheel drive make the 530d xDrive the confident tow car and winter cruiser. The 540i tows well too, but the diesel's low-end torque is better suited to it. |
| Enthusiast wanting the best sound and pace short of an M car | 540i (or step to M550i if budget allows) | The 540i is the sweet-spot straight-six petrol 5 Series. For more, the V8 M550i xDrive exists but is a pricier, thirstier conversation. |
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Frequently asked questions
Is the 540i quicker than the 530d?
Yes. The 540i (340 bhp) does 0-62 in around 4.8 to 5.1 seconds with xDrive, against roughly 5.4 seconds for the 530d (265 bhp). In-gear, the 530d's 620 Nm of torque keeps it very close for real-world overtakes, but the 540i is the quicker car outright and revs harder to the top end.
How much thirstier is the 540i?
Noticeably. The petrol 540i returns a real-world 28 to 36 mpg combined against the diesel 530d's 40 to 50 mpg. Over high annual mileage that difference is significant, and the 540i also sits slightly higher on insurance. If fuel economy is a priority, the 530d is the clear winner; if you do fewer miles, the gap matters less.
Are both the 530d and 540i ULEZ-compliant?
Yes. Every G30-generation 530d and 540i (2017 to 2023) uses Euro 6 engines and is ULEZ-compliant, so emissions-zone access is not a factor in choosing between them. This is a character and cost decision, not a compliance one.
Which engine is more reliable, the B57 or the B58?
Both are regarded as strong, well-engineered straight-sixes. The petrol B58 is one of BMW's most highly rated modern engines and is very durable when serviced. The diesel B57 is a robust performance diesel but carries the usual diesel maintenance items (DPF, EGR, AdBlue/SCR) that need healthy upkeep, particularly on short-journey cars. Service history matters more than the badge with either.
Should I get xDrive or rear-wheel drive?
The 530d is frequently specced as xDrive and makes an excellent all-weather long-distance cruiser; the 540i is also commonly xDrive in the UK. Rear-wheel-drive versions are lighter and slightly more economical and are fine for most conditions. If you tow or drive in poor weather, xDrive is worth having on either engine.
Is the 2020 LCI mild-hybrid a concern on these cars?
The 48V mild-hybrid (from the 2020 LCI) adds a belt-driven starter generator and a small 48V battery that smooth stop-start and add mild assist. These are emerging wear items but are covered under warranty for most cars in 2026, with out-of-warranty replacement typically a few hundred pounds up to around £1,800. It is not a reason to avoid the LCI cars, which bring the freshest tech and strongest residuals.
530d or 540i for towing?
Both tow well, but the 530d's 620 Nm of low-down torque makes it the more relaxed tow car, especially as an xDrive. The 540i has the power to tow comfortably too, but you will use more revs and more fuel doing it. For regular towing, the 530d xDrive is the natural choice.