A Ferrari 499P and a Cadillac V-Series.R can fight for the same overall victory because Balance of Performance brings them into one performance range. That does not make them the same type of car. The Ferrari is an LMH, developed as a manufacturer-specific vehicle concept. The Cadillac is an LMDh, built around a regulated platform of licensed and common components.
The most important distinction is not simply where the electric motor sits. It is who owns the architecture, which choices remain open and how the technical risk is divided between the manufacturer and its suppliers.
LMDh: a controlled platform
An LMDh manufacturer must use a chassis derived from one of four licensed suppliers: Dallara, Ligier, Multimatic or Oreca. The common hybrid package combines a Bosch motor-generator and control system, a Williams Advanced Engineering battery and Xtrac's P1359 seven-speed transverse gearbox.
The manufacturer still supplies the combustion engine, defines the bodywork and aerodynamics within the rules, and develops the vehicle's control strategy and identity. Those are substantial responsibilities, but they sit on a platform whose most expensive structural and hybrid choices have already been standardised.
That reduces the number of open technical problems. It can also reduce cost, development time and programme risk. LMDh is not a lesser engineering exercise; it is a deliberately narrower one.
LMH: responsibility for the whole concept
LMH gives the manufacturer responsibility for the complete car. The chassis is manufacturer-specific, while the combustion engine may be bespoke or derived from a production unit. Aerodynamic performance must fit the homologation window, but the route into that window is far less prescribed.
This freedom comes with a price. More components, interfaces and decisions belong to the manufacturer. The programme carries more design freedom and more technical exposure at the same time.
LMH is not restricted to the WEC. The Aston Martin Valkyrie competes in both the World Endurance Championship and IMSA's GTP class, proving that both regulatory routes can cross the Atlantic when a programme is homologated and entered for both series.
The front axle remains a visible difference
The common LMDh motor-generator is integrated into the rear transmission, so its electrical drive reaches the rear axle. An LMH may use a front MGU-K with electrical DC power of up to 200 kW. Positive torque may be delivered to the front wheels only at the speeds defined in the BoP, apart from specific procedural exceptions in the regulations.
When that deployment condition is met, the LMH can become temporarily four-wheel driven. That can change traction, balance and energy management, but it should not be described as an automatic advantage on every slow or wet corner. The threshold, circuit and conditions determine when the architecture becomes relevant.
The previous habit of comparing a 50 kW LMDh figure directly with the LMH limit of 200 kW is misleading because published LMDh figures have referred to different operating definitions. The sound comparison is architectural: rear-axle common hybrid versus a potentially front-driven LMH system.
BoP equalises outcomes, not engineering
BoP can adjust mass, power and other performance parameters. It cannot erase packaging, cooling, weight distribution, component ownership or the way a team develops and services the car. Those differences influence cost, reliability work, upgrade strategy and the way performance is produced.
Convergence without sameness
From 2026, an ERS is mandatory for every newly homologated LMH. Existing non-hybrid homologations can continue, which is why the naturally aspirated Aston Martin Valkyrie remains the exception on the 2026 grid.
The rule change narrows one part of the gap, but the larger distinction survives. LMDh controls cost by sharing the spine and hybrid hardware. LMH leaves the manufacturer responsible for the complete vehicle concept. BoP can bring their lap times together. It cannot make their development paths identical.