Most of that specialty equipment cost a lot, and I just did it simple.
Regardless if it's a Jog or Car Ride, my guys get Harness' put on them. What I did is just buy a couple inexpensive short Leash's, take the (human) loop end and stuff it down between the bottom and back of the seat, and tied it off where they couldn't be thrown into the Dash.
That gives them room to stand and look/sniff out the window, come over to my elbow and lay down if they want. When they're not riding, the leash's just lay flat and are out of the way.
Total cost <$10.
Weather permitting, when I have left them in the Vehicle, I always disconnect them, where they can run around and utilize the ACRE of room I'm insuring for their pleasure.
(I have a Suburban with the back cleared for them
)