Verstappen's Engine Braking Complaint Exposes Red Bull Power Unit Flaw Despite Mexico Win

Max Verstappen won the Mexico City Grand Prix on Sunday from fifth on the grid. It was his third victory of 2026, and it lifted him from fourth to second in the drivers’ championship. The more revealing line of the weekend came from Verstappen himself: as reported by Motorsport.com, he said the engine braking on Red Bull’s in-house power unit had been behaving in a “random” way and that he needed “a conversation” with it.

The result moved Red Bull forward. The complaint suggests the team is winning in spite of its engine rather than because of it, and with four rounds left that distinction matters.

A win from fifth that hid a fault

On the scoresheet, Mexico was close to an ideal afternoon for Red Bull. Verstappen took 25 points while the three drivers immediately around him in the standings all came away with fewer. Lewis Hamilton converted pole into second place. Charles Leclerc finished fourth from third. George Russell, who started alongside Hamilton on the front row, slipped to sixth. Andrea Kimi Antonelli, the runaway leader, took third from fourth on the grid.

Going into the weekend, Russell held second on 242 points, one ahead of Hamilton and six ahead of Verstappen. Coming out of it, Verstappen leads that group on 261, with Hamilton two points behind and Russell 11 adrift.

Isack Hadjar’s ninth place added two points to Red Bull’s constructors’ total, which now stands at 382, 17 clear of McLaren in the battle for third. The sister RB F1 Team, which runs the same power unit, had a mixed day. Liam Lawson drove from 22nd on the grid to seventh, the most striking climb of the race, while Arvid Lindblad retired after starting eighth.

So the engine is not slow, and it is not fragile in any way that showed up on Sunday. Verstappen’s complaint is about something subtler: whether the car does the same thing every time he lifts off the throttle.

Why “random” engine braking costs lap time

Engine braking is the deceleration a car gets from its power unit when the driver comes off the throttle. In the naturally aspirated era, that was mostly mechanical resistance from the engine itself. In the hybrid era, a large share of it comes from the MGU-K, the motor-generator on the crankshaft, which harvests energy for the battery by resisting the rear wheels.

Because that harvesting would otherwise upset the car’s brake balance, Formula 1 uses brake-by-wire on the rear axle. The system decides, corner by corner, how much rear stopping force comes from the hydraulic brakes and how much from the MGU-K, and it tries to keep the total consistent. When it works, the driver feels a predictable rear axle. When it doesn’t, the rear can lock or step out on turn-in at one corner, then refuse to rotate at the next.

The 2026 regulations raise the stakes considerably. The MGU-H has gone, and the MGU-K’s output has roughly tripled to 350kW, with electrical power now close to half the total. That makes the MGU-K a far bigger part of the rear braking picture than it was in the previous generation. Any inconsistency in how much it harvests, whether from battery state of charge, deployment strategy or software calibration, is magnified accordingly.

A driver of Verstappen’s calibre can cope with a car that is difficult. A car that is unpredictable is another matter, because he cannot commit to a braking point he does not trust. “Random” is a pointed choice of word. It suggests the problem is inconsistency rather than a fixed trait Red Bull can engineer around.

There is precedent at this team. In 2014, the first year of the hybrid rules, Sebastian Vettel struggled badly with rear stability on corner entry in the RB10. That was partly a brake-by-wire and engine-braking problem, and partly the loss of the exhaust-blown diffuser he had built his driving around. Daniel Ricciardo adapted faster and beat him. The lesson then was that the energy recovery system shapes how a car feels into a corner as much as how fast it comes out of one.

Mexico’s altitude may have flattered Red Bull

The Autódromo Hermanos Rodríguez sits 2,286 metres above sea level, far higher than any other venue on the calendar. The thin air cuts downforce, drag and cooling, forces the turbocharger to work much harder and reduces what the combustion engine can produce. With less aerodynamic grip and less drag slowing the car, the long braking zones depend more heavily on the brakes and on the power unit’s behaviour on the overrun.

In one sense, that makes Verstappen’s win more impressive: he was dealing with an awkward rear axle at the circuit where it is hardest to hide one. In another, it means Mexico is a poor guide to what comes next. The grip deficit at altitude compresses the field and blunts aerodynamic advantages, a pattern that has produced unusual results in Mexico for a decade. Mercedes have won 12 of the 19 rounds this year, so their drivers finishing third and sixth here says more about the venue than about any shift in form.

Interlagos, scene of Sunday’s Brazilian Grand Prix, sits at around 800 metres. That is high enough to matter, but nothing like Mexico. Its short, anticlockwise lap includes the heavy stop into the Senna S and the downhill braking into Turn 4, both corners where a nervous rear on entry is punished immediately. If Red Bull’s engine braking remains erratic, Brazil is where it will show.

Four drivers, 16 points and the scrap for second

Antonelli’s 119-point lead, built on nine wins, has all but settled the title. The live contest is the one behind him:

Position	Driver	Team	Points	Gap to second
2	Max Verstappen	Red Bull	261	–
3	Lewis Hamilton	Ferrari	259	2
4	George Russell	Mercedes	250	11
5	Charles Leclerc	Ferrari	245	16

Second place carries no trophy, but it means something to all four. For Hamilton, it would be his best championship finish since he joined Ferrari. Russell wants it to show he can stand alongside a team-mate who has won nine times. For Verstappen, it would rescue a season in which Red Bull have won three Grands Prix to Mercedes’ 12.

The structural problem for Verstappen is that he is effectively on his own. Ferrari bring two cars to every race, and between them Hamilton and Leclerc can take points off their rivals. Russell drives the season’s benchmark car and, on most circuits, should be quicker than anyone else in this group. Hadjar, eighth in the standings on 107 points, has not been close enough to the front to take points away from Verstappen’s rivals.

That leaves Verstappen relying on outright pace and consistency over four rounds. An engine braking quirk that costs a tenth here, or a moment of hesitation into a hairpin there, is exactly the kind of margin that decides a two-point fight.

Red Bull Powertrains owns this problem now

When Red Bull decided to build its own power unit, with Ford as a partner, part of the argument was control. The team had spent years publicly frustrated with Renault during the early hybrid era, and later relied on Honda. Bringing the engine in-house meant no longer depending on a supplier’s priorities. It also means no longer having anyone else to blame.

The encouraging news for Milton Keynes is that this looks like a calibration problem rather than a hardware one. Engine braking behaviour lives largely in software: harvest maps, brake-by-wire targets and the interaction between energy management and the driver’s pedal. Those can be changed between races without touching the homologated hardware. Lawson’s charge through the field in Mexico suggests the package has real performance when the driver can exploit it.

The less encouraging news is that inconsistency is the hardest kind of fault to fix in a week. If the behaviour were wrong but repeatable, engineers could map around it. “Random” implies they first have to find out why it varies. That work will probably run through the winter, and it will shape how competitive Red Bull’s power unit is in 2027 far more than any change made before Brazil.

For the rest of 2026, I expect Verstappen to hold second only if Red Bull can give him a rear axle he trusts by Interlagos. The bigger threat is Russell in the faster car, not Hamilton. If Verstappen is still talking about engine braking on Thursday in São Paulo, Mercedes will be favourites to finish first and second in the championship.