function X1()
    X1 = Dict{Symbol,Float64}()

    # Mass and Moments of Inertia
    X1[:G]   = 9.80665                                                 # standard (Earth) gravity (m/s^2)
    X1[:mfl] = 484                                                     # weight at front left wheel (kg)
    X1[:mfr] = 455                                                     # weight at front right wheel (kg)
    X1[:mrl] = 521                                                     # weight at rear left wheel (kg)
    X1[:mrr] = 504                                                     # weight at rear right wheel (kg)
    X1[:m]   = X1[:mfl] + X1[:mfr] + X1[:mrl] + X1[:mrr]               # total vehicle mass (kg)
    X1[:Ixx] = 175                                                     # pitch moment of inertia (kg*m^2)
    X1[:Iyy] = 1000                                                    # roll moment of inertia (kg*m^2)
    X1[:Izz] = 2900                                                    # yaw moment of inertia (kg*m^2)

    # Dimensions
    X1[:L]  = 2.87                                                     # wheelbase (m)
    X1[:d]  = 1.63                                                     # track width (m)
    X1[:a]  = (X1[:mrl] + X1[:mrr])/X1[:m]*X1[:L]                      # distance from CG to front axle (m)
    X1[:b]  = (X1[:mfl] + X1[:mfr])/X1[:m]*X1[:L]                      # distance from CG to rear axle (m)
    X1[:hf] = 0.1                                                      # front roll center height (m)
    X1[:hr] = 0.1                                                      # rear roll center height (m)
    X1[:h1] = 0.37                                                     # CG height w.r.t. line connecting front and rear roll centers (m)
    X1[:h]  = X1[:hf]*X1[:b]/X1[:L] + X1[:hr]*X1[:a]/X1[:L] + X1[:h1]  # CG height (m)
    X1[:ab] = X1[:a] + 0.4953                                          # distance from CG to front bumper (m)
    X1[:bb] = X1[:b] + 0.4318                                          # distance from CG to rear bumper (m)
    X1[:w]  = 1.87                                                     # physical width (m)

    # Tire Model Parameters
    X1[:μ] = 0.92                                                      # coefficient of friction
    X1[:Cαf] = 150e3 # 140e3                                           # front tire (pair) cornering stiffness (N/rad)
    X1[:Cαr] = 220e3 # 190e3                                           # rear tire (pair) cornering stiffness (N/rad)

    # Longitudinal Actuation Limits
    X1[:Fx_max] = 5600                                                 # max positive longitudinal force (N)
    X1[:Px_max] = 75e3                                                 # max motor power output (W)

    # Longitudinal Drag Force Parameters (FxDrag = Cd0 + Cd1*Ux + Cd2*Ux^2)
    X1[:Cd0] = 241.0                                                   # rolling resistance (N)
    X1[:Cd1] = 25.1                                                    # linear drag coefficint (N/(m/s))
    X1[:Cd2] = 0.0                                                     # quadratic "aero" drag coefficint (N/(m/s)^2)

    # Drive and Brake Distribution
    X1[:fwd_frac] = 0.0                                                # front wheel drive fraction for implementing desired Fx
    X1[:rwd_frac] = 1 - X1[:fwd_frac]                                  # rear wheel drive fraction for implementing desired Fx
    X1[:fwb_frac] = 0.6                                                # front wheel brake fraction for implementing desired Fx
    X1[:rwb_frac] = 1 - X1[:fwb_frac]                                  # rear wheel brake fraction for implementing desired Fx

    # Computed Longitudinal Limits
    X1[:Fx_min] = max(-X1[:m]*X1[:G]*X1[:a]*X1[:μ]/(X1[:L]*X1[:rwb_frac] + X1[:μ]*X1[:h]),    # brake force corresponding to first of
                      -X1[:m]*X1[:G]*X1[:b]*X1[:μ]/(X1[:L]*X1[:fwb_frac] - X1[:μ]*X1[:h]))    # the front or rear tire saturating (N)
    X1[:Ax_max] = X1[:Fx_max]/X1[:m]                                   # longitudinal acceleration corresponding to Fx_max (m/s^2)
    X1[:Ax_min] = X1[:Fx_min]/X1[:m]                                   # longitudinal acceleration corresponding to Fx_min (m/s^2)

    # Steering Limits
    X1[:δ_max] = 18*pi/180                                             # maximum steering angle, 2 wheel mode (radians)
    X1[:κ_max] = tan(X1[:δ_max])/X1[:L]                                # maximum curvature, relevant at low speeds (1/m)

    X1
end
