BMW 5 Series M550i V8.
What to Check Before Buying.

The BMW 5 Series M550i V8 suits enthusiastic drivers seeking executive comfort with serious performance, offering a compelling middle ground between the standard 5 Series and the full M5. This variant's 4.4-litre twin-turbo V8 delivers 530bhp and covers 0-60mph in just 3.6 seconds, making it devastatingly quick for a luxury saloon. However, fuel economy averages just 25-28mpg in real-world driving, and road tax sits in the premium bracket due to CO2 emissions exceeding 255g/km. When buying used, check the service history meticulously as the S63 engine requires oil changes every 10,000 miles maximum to prevent premature wear. Inspect the adaptive suspension for leaks or failure, as repairs prove expensive. Verify the xDrive all-wheel-drive system operates smoothly without binding or vibration. Check for software updates at BMW dealers, as early models benefited from ECU refinements. Budget for premium tyres, as the M550i wears through rear rubber quickly under enthusiastic use. This variant typically commands a £10,000-15,000 premium over equivalent 530d models on the used market.

The average used car has 3+ known model faults the seller won't mention.