I was half joking - but it might be done.
If the wheel is built in multiple segments, like the armature of a dc brushed motor - and you rewound that armature with many more turns on each pole, and connected them to the commutator such that (say) only 4 at a time at the bottom of the 'wheel', only those 4 as the 'wheel' turned were energised using the original brush set... such that only those in close contact with the ground were energised to give you extra grip.........
ie your 'wheels' are made from old armatures - eg from windscreen wiper motors....
but maybe fat squashy tyres and extra weight might acheive the same much more simply.
Or adding many powerful permanent magnet fixed to the vehicle but a little above the steel floor would acheive the same equivalent of weight without adding mass.............. alternate N and S would be a good idea.
regards
Allan