You drive to a motorway service station, and embark in a podule in much the same was as for the Eurostar, but only one vehicle goes in each podule.
You select your destination service station or other terminus - but let's imagine service stations only for now - and hit 'go'.
Your podule moves off on a special track that takes it to the carriageway in the central reservation on which traffic is going in the right direction, where it accelerates and joins the flow of other podules already travelling along.
You don't need to drive, there's no overtaking possible as it's a linear stream of podules, speed is governed by the traffic routing computer in overall charge of the system and podule density can be maybe three times higher than if you were driving yourself on the regular motorway.
As you approach your destination, you're automatically routed off the carriageway into a deceleration lane and into the service station where you drive out of the podule and resume control of your vehicle to travel again on regular roads.
I favour linear induction motors for the motive force, powered by solar collectors mounted above the new podule carriageways.