Now in their second year with Bob Bell (chassis) and Rob White (engine) as technical heads, this is also the second year of the 72-degree engine. This second generation engine has had the development time its predecessor lacked, and as a result its weight and power output were on a par with the opposition. The former benefit has had clear advantages for the team, as the 2004 engine was by the team's own admission overweight as a result of its truncated development cycle.
With less weight being taken up by the engine, and a weight loss programme around the car, the R25's weight distribution was more akin to its rivals. At the rear the team used a six speed gearbox; this has often been cited as a mark of the engine's drivability, but also the weight and complexity benefits of one less ratio were a factor for Renault, perhaps still mindful that the engine isn't where it needs to be weight wise.
Towards the front the much talked about V keel was a variation on the common single keel; the design is simply a V shaped structure to pass the lower wishbone loads into the chassis, simpler and lighter. The keel also allowed for some flow to pass between its legs, although this was probably a secondary benefit.