BMW X3 G45SUV2024–present
Every powertrain fitted to the G45-generation BMW X3 — from the 2.0-litre B48 four-cylinder mild-hybrid to the 3.0-litre B58 six-cylinder M50 and the B57 six-cylinder diesel.
Real UK costs, honest reliability data, and the B58's defining role in this generation's ownership story.
Backed by real UK X3 enquiries in 2025 [BMW-VERIFIED].
Engine Database
Every powertrain fitted to the G45 X3 specifically — from the 2024 launch through current production, covering mild-hybrid petrol, diesel, and plug-in hybrid variants.
Overview
The BMW X3 G45 is the fourth generation of the BMW X3 compact luxury crossover SUV, produced since August 2024. Built on BMW's CLAR platform, the G45 succeeds the G01 and features a range of mild-hybrid and plug-in hybrid powertrains. The engine line-up at launch included the 20 xDrive (2.0-litre B48 four-cylinder mild-hybrid petrol), xDrive20i (2.0-litre B48), 30e xDrive (2.0-litre B48 plug-in hybrid), and M50 xDrive (3.0-litre B58 six-cylinder mild-hybrid petrol).
A 20d xDrive (2.0-litre B47 four-cylinder diesel mild-hybrid) was also available from launch, and the 40d xDrive (3.0-litre B57 six-cylinder diesel) was introduced in 2025. Unlike its predecessor, the G45 no longer has a battery electric variant built on the same platform; the electric iX3 is now based on a separate Neue Klasse platform.
Key Facts
Market Intelligence
The G45 X3 is BMW's latest-generation compact SUV; enquiries are concentrated on the B48 petrol and B47 diesel variants, with values ranging from £40,000 for entry-level 20d examples to £65,000+ for well-specced M50 models.
04Best & Worst Engines
Best Petrol Overall
B58B30P 3.0-litre six-cylinder (M50 xDrive) — The 398 PS B58 is widely regarded as BMW's most reliable modern six-cylinder. Delivering 580 Nm of torque and 0-62 in 4.6 seconds, it offers genuine performance SUV capability with proven durability. The TU2 version (B58B30M2) adds improvements.
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Who it's for: buyers who want the ultimate performance X3 with proven reliability.
Best Diesel Overall
B57D30B 3.0-litre six-cylinder (40d xDrive) — The 303 PS B57 six-cylinder diesel delivers effortless torque, excellent refinement, and genuine durability for high-mileage touring. Introduced in 2025, it features a mild-hybrid system with the electric motor integrated into the transmission.
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Who it's for: high-mileage buyers who want effortless torque and excellent economy.
Highest Risk
B48B20M0 (early xDrive20i) — While the B48 is generally reliable, early production units may have cooling system issues (water pump, expansion tank). Coolant leaks are the primary concern on higher-mileage examples.
“”
Who it's for: buyers who accept the premium and maintain the cooling system proactively.
Most Expensive Failure
B58B30P/B58B30M2 (M50 xDrive)
“The 3.0-litre six-cylinder is the most expensive powertrain in the G45 line-up to replace, with reconditioned units costing £4,800–£8,000. HPFP and cooling system issues are the primary risks.”
Best Value
B47D20B 2.0-litre diesel (20d xDrive) — The 197 PS B47 diesel offers the best balance of performance, economy, and running costs. It's the most economical G45 engine, parts are widely available, and the recon cost is the lowest in the range. Post-recall EGR cooler units are reliable.
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Who it's for: buyers who prioritise running costs.
Most Overlooked
B48B20V 2.0-litre PHEV (30e xDrive) — Often overlooked by buyers who default to the petrol or diesel, the 30e delivers 299 PS combined output with up to 56 miles of electric range. The 19.7 kWh battery and 135 kW electric motor make it the ultimate company car choice.
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Who it's for: company car buyers and urban commuters who want EV capability without range anxiety.
Best Petrol Overall
B58B30P
3.0-litre six-cylinder (M50 xDrive) — The 398 PS B58 is widely regarded as BMW's most reliable modern six-cylinder. Delivering 580 Nm of torque and 0-62 in 4.6 seconds, it offers genuine performance SUV capability with proven durability. The TU2 version (B58B30M2) adds improvements.
“”
Who it's for: buyers who want the ultimate performance X3 with proven reliability.
Best Diesel Overall
B57D30B
3.0-litre six-cylinder (40d xDrive) — The 303 PS B57 six-cylinder diesel delivers effortless torque, excellent refinement, and genuine durability for high-mileage touring. Introduced in 2025, it features a mild-hybrid system with the electric motor integrated into the transmission.
“”
Who it's for: high-mileage buyers who want effortless torque and excellent economy.
Highest Risk
B48B20M0
(early xDrive20i) — While the B48 is generally reliable, early production units may have cooling system issues (water pump, expansion tank). Coolant leaks are the primary concern on higher-mileage examples.
“”
Who it's for: buyers who accept the premium and maintain the cooling system proactively.
Most Expensive Failure
B58B30P/B58B30M2
(M50 xDrive)
“The 3.0-litre six-cylinder is the most expensive powertrain in the G45 line-up to replace, with reconditioned units costing £4,800–£8,000. HPFP and cooling system issues are the primary risks.”
Best Value
B47D20B
2.0-litre diesel (20d xDrive) — The 197 PS B47 diesel offers the best balance of performance, economy, and running costs. It's the most economical G45 engine, parts are widely available, and the recon cost is the lowest in the range. Post-recall EGR cooler units are reliable.
“”
Who it's for: buyers who prioritise running costs.
Most Overlooked
B48B20V 2.0-litre PHEV (30e xDrive) — Often overlooked by buyers who default to the petrol or diesel, the 30e delivers 299 PS combined output with up to 56 miles of electric range. The 19.7 kWh battery and 135 kW electric motor make it the ultimate company car choice.
“”
Who it's for: company car buyers and urban commuters who want EV capability without range anxiety.
Engine
Typical Mileage
Common Major Failure
Repair Cost (Specialist)
Replacement Cost (Recon)
Ownership Verdict
Best Petrol -reliable four-cylinder
Watch -battery adds complexityPremium Choice -performance costsBest Diesel -most economicalSolid Choice -six-cylinder refinementEngineTypical MileageCommon Major FailureRepair Cost (Specialist)Replacement Cost (Recon)Ownership VerdictBest Petrol -reliable four-cylinderWatch -battery adds complexityPremium Choice -performance costsBest Diesel -most economicalSolid Choice -six-cylinder refinement
The G45 rule
A £4,800–£8,000 B58 recon against a £40,000–£50,000 G45 sits at 10–20% of the car's value -safe. Against a well-kept £55,000+ example, the same recon drops to a routine 9–15% -a repair decision, not a financial one. For a modern premium SUV, the 70% BMW threshold rarely applies, but we'll still honestly tell you when a repair doesn't make sense.
Key Takeaways
Which G45 Costs Least To Own?
B47 20d -cheapest recon, best economy.
Which G45 Costs Most To Own?
B58 M50 -HPFP and cooling system repairs add cost.
Which G45 Is Best Value?
B47 20d -the sweet spot between economy, performance, and running costs.
B48
Cooling System Leaks
Affected models:
G45 20 xDrive, xDrive20i, 30e xDrive (B48 family).
Typical failure mileage:
40,000–80,000 miles.
Root cause:
The cooling system on B48 engines -including the expansion tank, water pump, and plastic fittings -can develop leaks over time. Coolant loss can lead to overheating and, if ignored, engine damage. The low-temperature coolant circuit is a particular area of concern.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£500–£1,200
£300–£800
Water pump, expansion tank, coolant pipes
Catastrophic (Replacement)
Dealer
Specialist
£4,000–£7,000
£3,200–£5,500
Full reconditioned engine
Our Recommendation
On any G45 petrol approaching 40,000 miles, have the cooling system inspected -a £300–£800 preventative repair is cheaper than the £3,200–£5,500 replacement that follows if ignored.
B58
High-Pressure Fuel Pump (HPFP) Failure
Affected models:
G45 M50 xDrive (B58B30P/B58B30M2).
Typical failure mileage:
30,000–60,000 miles.
Root cause:
The high-pressure fuel pump on B58 engines can fail, leading to long cranking times before the engine starts, noticeable loss of power, engine misfires, and even stalling. The issue can be intermittent, making diagnosis challenging.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£1,200–£2,000
£800–£1,500
HPFP replacement, fuel system flush
Catastrophic (Replacement)
Dealer
Specialist
£5,500–£9,000
£4,800–£8,000
Full reconditioned engine
Our Recommendation
If your G45 M50 exhibits long cranking or power loss, have the HPFP inspected immediately -an £800–£1,500 preventative repair is cheaper than the £4,800–£8,000 replacement that follows if ignored.
B47/B57
Diesel EGR Cooler & DPF Issues
Affected models:
G45 20d xDrive (B47D20B) and 40d xDrive (B57D30B).
Typical failure mileage:
60,000–120,000 miles.
Root cause:
The EGR cooler on B47 and B57 diesel engines can develop internal coolant leaks, leading to coolant loss. DPF blockage is also common on cars used predominantly for urban driving. The 48V mild-hybrid system adds some complexity to the diesel powertrain.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£800–£1,500 (EGR recall work free if applicable)
£500–£1,200
EGR cooler replacement, DPF regeneration
Catastrophic (Replacement)
Dealer
Specialist
£4,000–£6,000
£2,800–£5,000
Full reconditioned engine
Our Recommendation
On any G45 diesel, check the EGR cooler recall status immediately and ensure regular motorway runs for DPF regeneration -a £500–£1,200 preventative service is cheaper than the £2,800–£5,000 replacement that follows if ignored.
VariantEngine Code
Used (Supply)
Reconditioned (Supply)
Rebuilt (Supply)
Labour Hours
Diesel Variants
Petrol Variants
Scope note: All variants listed are G45 X3 only. The G48 (long-wheelbase) variant for the Chinese market shares the B48 petrol engines but is covered on its own Generation Page. The 40d xDrive was introduced in 2025. The M50 xDrive is the performance flagship, producing 398 PS and 580 Nm of torque.
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£2,800–£8,000 supply-only
[BMW-QUOTE]
Most Common Failures
Live FeedBMW X3 20d xDrive G45
B47
Birmingham
Coolant loss, EGR cooler3
enquiries
Updated MonthlyBMW X3 M50 xDrive G45
B58
LondonLong cranking on startup2
enquiries
Updated MonthlyBMW X3 xDrive20i G45
B48
ManchesterCoolant system warning2
enquiries
Updated MonthlyMost Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£2,800–£8,000 supply-only
[BMW-QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£2,800–£8,000 supply-only
[BMW-QUOTE]
Most Common Failures
Diesel Variants
Petrol Variants
Scope note: All variants listed are G45 X3 only. The G48 (long-wheelbase) variant for the Chinese market shares the B48 petrol engines but is covered on its own Generation Page. The 40d xDrive was introduced in 2025. The M50 xDrive is the performance flagship, producing 398 PS and 580 Nm of torque.
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£2,800–£8,000 supply-only
[BMW-QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£2,800–£8,000 supply-only
[BMW-QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£2,800–£8,000 supply-only
[BMW-QUOTE]
Most Common Failures
Live FeedBMW X3 20d xDrive G45
B47
BirminghamCoolant loss, EGR cooler3
enquiries
BMW X3 M50 xDrive G45
B58
LondonLong cranking on startup2
enquiries
BMW X3 xDrive20i G45
B48
ManchesterCoolant system warning2
enquiries
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