Background Scale-model road systems such as Faller https://www.faller.de utilise vehicles that follow a ferromagnetic wire embedded in the road surface. The vehicles operate at full speed and continue until the on-board rechargeable battery runs out. There is limited remote control. At strategic places an electromagnet under the track can operate an on/off sensor in the vehicle.
Problem This on/off behaviour - for example at a bus stop or road junction brings the vehicle to an abrupt and very unrealistic stop. The wheels are driven via a worm (screw) gear so the wheels lock when the motor stops. Video showing abrupt stop and start https://youtu.be/emejjaj3c6E?t=411
Question More complex and expensive digital systems are commercially available that simulate realistic acceleration and braking behaviour. Nevertheless, can I make a simple analog circuit to simulate inertia in these tiny vehicles?
My naive solution I would like to put a capacitor in series with a resistor across the motor terminals. When battery power is switched off, the capacitor continues to power the motor until it is discharged. Likewise, on switching on the current, the motor starts slowly whilst the capacitor is charging. The component values can be adjusted to give realistic artificial inertia according to the size of the vehicle, e.g. Lorries will take longer to stop than cars.
Envisaged problems Components have to be small (tiny) to fit on an HO (1:87) scale model. I think that I will need a huge capacitor to power the motor as it discharges. Is my idea sound - even in principle - or there another simple solution?
NOTE These vehicles are only required to go in a forward direction - no reversing needed.
P.S. I'm thinking that by using a power transistor (op amp?) to detect the on/off switch, I could reduce the size of the capacitor and raise the value of the resistor by applying them to the input of the op amp. Haven't thought this through yet.
EDIT Technical specs found so far:-
(a) I measured resistance across the motor terminals - 1 ohm
(b) The battery is a Varta V 150 H; Rechargeable Ni-MH Button; 1.2 V
(c) I was able to measure the current - 28 mA
(d) I found a circuit diagram (unofficial) http://simgw.cosmos.ehime-u.ac.jp/~shimizu/fallercar1/carsys032.jpg
EDIT Electromagnets are mounted under the track at strategic points where a stop may be required, The vehicle is steered by a permanent magnet that follows the under-track passive ferromagnetic wire. There is a reed switch inside the vehicle that detects the on-or-off-ness of the electromagnet and disconnects the battery from the motor accordingly.