G-Power makes BMW M850i more powerful than the standard M8
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German tuning company G-Power has unveiled a new take on the discontinued BMW M850i, whose 4.4-litre V8 produces 456 kW and 850 Nm after a software upgrade. Power rises by 66 kW, while top speed can increase to 300 km/h. The engine upgrade costs just €2,495, but carbon-fibre bodywork, a sports exhaust and new wheels can multiply the cost of the conversion.
M850i enters M8 power territory
The M850i Bi-Turbo unveiled by G-Power is based on the BMW 8 Series coupé, which BMW discontinued in 2026.
The factory 4.4-litre twin-turbocharged V8 produces 390 kW and 750 Nm. G-Power's GP-620 software increases those figures to 456 kW and 850 Nm.
For comparison, the standard BMW M8 offered 441 kW, while the more powerful M8 Competition produced 460 kW. The tuned M850i therefore exceeds the former's output and falls just 4 kW short of the latter.
According to BMW's factory figures, the M850i accelerates to 100 km/h in 3.7 seconds. G-Power has not published acceleration figures for the upgraded car. Raising the top speed to 300 km/h requires the electronic speed limiter to be removed separately. This costs €495. Extending the digital instrument cluster's speed display to 330 km/h adds another €395 to the bill.
Carbon fibre changes the coupé's appearance
G-Power also offers a carbon-fibre bonnet, rear wing and other aerodynamic components for the M850i.
The demonstration car was fitted with a sports exhaust with four carbon-fibre tips and 21-inch Hurricane RS wheels.
The price list clearly shows how quickly an affordable engine tune can become an expensive project. The sports exhaust costs €4,760, the carbon-fibre bonnet €7,140 and the wheel set €8,806.
With additional engine components, instrument cluster modifications and exterior changes, the total cost of the conversion can exceed €36,000.
G-Power also offers the more powerful GP-670 package, which raises the V8's output to 493 kW and 900 Nm. Its price starts at approximately €13,015.
Does a €2,500 tune make sense?
The GP-620 power upgrade is attractively priced, but it does not automatically turn the M850i into an M8.
The M8 comes from the factory with more extensively modified chassis components, brakes and cooling system. These affect the car's capabilities, particularly during longer sessions on track, where engine power alone is not enough.
Nor is the GP-620 an entirely new solution. G-Power has offered this level of power before, and the latest project demonstrates its continued use in upgrading the 8 Series.
Owners in Europe must also take account of type approval for the conversion, emissions requirements and insurance terms.
The greatest value of G-Power's package lies in the opportunity to make the luxurious M850i considerably more powerful at relatively little cost. But if the aim is an overall driving experience comparable to the M8's, a software upgrade is no substitute for the performance model's more extensively engineered hardware.
