Propagation characteristics in vehicular radio channels are affected by time- and frequency-selective behavior due to the multipath propagation effect and the movements of the transmitter, the receiver as well as the relevant scatterers. Measurements are vital for the understanding of propagation channels. This article provides an overview of existing vehicular channel measurements. The vehicular channel measurement techniques are briefly described and classified. Furthermore, we review the channel metrics such as path-loss, signal fading and Doppler spread based on the available literature and we summarize and discuss some measurements results of the reported parameters to describe the propagation narrowband channel characteristics in vehicular environments.