BMW 420i xDrive Gran Coupé (N20): Stage 1 + xHP Stage 3, 269bhp & 417Nm

This BMW 420i xDrive Gran Coupé runs the earlier N20 2.0 turbo petrol, and it came in for our Stage 1 custom dyno tune with an xHP Stage 3 calibration for the ZF 8-speed.

The numbers

It made 178bhp and 276Nm on the baseline run and left making 269bhp and 417Nm, more power and torque than a standard 428i:

Over 100Nm extra across the whole run

Tuned, this 420i holds around 390Nm or more from 2,200 to 4,500rpm, carries over 100Nm extra across the entire run and keeps pulling past 260bhp all the way to 6,200rpm. xHP Stage 3 lets the 8-speed handle that extra torque properly, with quicker, sharper shifts.

How it was done

Diagnostics and a health check first, baseline runs on our 4WD linked dyno, then a calibration developed with live data logging and repeated runs before the gearbox was flashed with xHP Stage 3 and the final verification pulls were done. No generic files, original software backed up and fully reversible.

Got a 4 Series? See our BMW 4 Series tuning figures, check your car’s gains and price, or read about the B48 420i Gran Coupé we tuned.