The variation of the power spectra (e¿) of the fluctuating Els¿sser variables ΔZ¿ with the solar wind velocity has been examined by either individual case study or statistical analysis with Helios data obtained near solar minimum. It is found, when going from high-speed to low-speed wind, that: 1) The slopes of both energy spectra systematically increase toward the value given by Kolmogorov's law. 2) The power density of &sgr;Z+ in the Alfv¿nic regime above f≈2¿10-4 Hz strongly decreases while the power density of ΔZ- does not change a lot. 3) A somewhat higher level of e- is found in the leading edges of high-speed streams near the regions of large velocity shear. We also found that density fluctuations might make some contributions to e- in the low-frequency domain. The relevance of these findings with respect to the evolution of the solar wind MHD turbulence is discussed. ¿ American Geophysical Union 1990