Classical methods are employed to characterize the energy-loss straggling for swift, heavy ions interacting with independent electrons of a degenerate electron gas. The method of Bohr on the statistical aspects of the energy-loss process is used, and the electron-intruder collision is modeled via a finite-range screened Coulomb potential energy. The transport fluctuation cross section is calculated analytically within the framework of the impact-parameter method. Comparison with straggling data obtained for carbon foils with singly ionized carbon ions is made, and a good agreement is found in the validity range of the applied classical methods.