In this paper a per unit scale saliency-and saliency shift equation are used to predict the saliency based position sensorless control performance of synchronous machines for EV drives by means of a finite element package. These equations are used in a comparative study of various types of synchronous machines. The machine drives investigated and compared are a reluctance synchronous machine (RSM) hybrid EV drive and two variable gear RSM EV drives. Also included in the investigation are two field intensified permanent magnet (FI-PM) EV drives with asymmetric rotors, one FI-PM machine with a symmetric rotor and one field weakening interior permanent magnet drive. The saliency shift of the different FI-PM machine rotor topologies are also investigated. Closed loop saliency based position sensorless control shows startup torque capabilities of up to 304 Nm of a 32 kW 6-pole RSM. The RSM EV machine is used to investigate possible design modifications to improve on the saliency ratio and shift of synchronous machines. Index Terms-Position sensorless control, EV drives. NOMENCLATURE AND DEFINITIONS Symbols: u, i, ψ Voltage current and flux linkage r, L Resistance and inductance T m , Θ Mechanical torque and inertia T ripple Torque ripple f Machine frequency φ Current angle θ r , ω r Rotor-angle and speed θ e , ω e Electrical-rotor angle and speed Δ, Σ Difference and sum Indices: s, r Stator and rotor α, β Stator fixed cartesian axes d, q Rotor fixed direct and quadrature axes c Carrier frequencyScalar values are written in normal letters, e.g. R or τ , vector values are written in small bold letters, e.g. i or ψ. Subscripts describe the location of the physical quantity, e.g. r s is the stator resistance. Superscripts specify the reference frame of the quantity, e.g. i r s is the stator current vector in the rotor reference frame. Estimated quantities are indicted with a hat, e.g.θ e . Small signal values are represented with δ.