Welcome  in  Mr  new  guy.
a  moving  vehicle  is  going  to  be  tricky.   Slot  cars,  unless  they  have  changed  in  the   many  long  decades  since  I  have  messed  with  them,  have  integral  motors  and  gears  (  motors  and  gears  built  into  the  frame.  this  makes  it  hard  to  do  any  modifications,   If  there  are  commercial  mods  available,  whey  will  be  for  more  speed,  and  not  less.
With  trains,  the  motors  are  separate,  and  can  be  replaced  with  gear  head  motors   to  get  very  slow  smooth  operation.
One  possibility  might  be  making  a  horse  powered  trolley,  which  looked  much  like  early  electric  trolleys,  except  for  the  horse  in  front   Bachman  makes  a  lot  of  stuff  in  On30   (  O  scale  narrow  gauge  30 inches  between  the  rails)    This  uses  the  same  gauge  (distance  between  the  rails)  as  Ho  gauge  standard  gauge,  but  in  O  scale ( 1/4  inch  to  the  foot  I  think).   I'm  thinking  most  of  the  Christmas  village  stuff  approximates    O  scale.
The  early  On30  enthusiasts  used  HO  scale  mechanisms,  now  Bachman  makes  lots  of  stuff,  greatly  expanding  what  is  possible  in  O  scale  narrow  gauge.   I  recommend  looking  at  this  stuff,  the  detail  is  awesome,  and  it  may  end  up  looking  much  better  than  the  lionel.
Good  luck,  look  around  here,  not  enough  traffic  at  this  site,  but  there  is  a  lot  of  good  projects  going  on  here  and  much  to  learn.
Bill  Nelson