This article investigates a front-wheel-drive battery electric vehicle. Using the coast-down resistance curve obtained from on-road tests, energy-flow measurements were conducted on a chassis dynamometer under both a standard ambient driving cycle and the subsequent ambient-temperature charging process. The results indicate that the efficiencies of the electric drivetrain, on-board charger, and battery pack during charge/discharge are within normal ranges, whereas the brake-energy recuperation rate is low and losses due to rolling resistance and aerodynamic drag account for a significant proportion of the total energy expenditure. Without altering the exterior styling, the optimisation effort therefore focused on reducing the tyre rolling-resistance coefficient and recalibrating the coast-down braking-torque map. Experimental validation shows that the recovered brake energy increased from 10.689 kW·h to 12.427 kW·h a gain of 16.3% and the driving range improved from 389 km to 410 km, corresponding to a 5.4 % enhancement.