[MrFlippant]

As usual they are a hefty bit of kit with the standard Carrera hallmark of a reverse polarity switch for running the other way round the track. However, there appears to be something like a digital chip fitted at the front end. They are definitely both analogue cars which work just fine on my track and, as with the full size car, there are no lights fitted so what is this stuff? Anybody know?

Wow. That checks all the boxes for a digital chip. You didn't show the bottom of the chassis, but I assume you've checked for an LED and found none?

The digitally chipped car will work fine on analog, though usually with full brakes all the time, depending on how the brakes work on your controller. PWM braking can sometimes work on their chips.