------------------------ 
-- Keep players in vehicles 
g_checkPedIndex = 0 
  
TimerManager.createTimerFor("raceresource","warppeds"):setTimer( 
    function () 
        -- Make sure all players are in a vehicle 
        local maxCheck = 6      -- Max number to check per call 
        local maxWarp = 3       -- Max number to warp per call 
  
        local warped = 0 
        for checked = 0, #g_Players - 1 do 
            if checked >= maxCheck or warped >= maxWarp then 
                break 
            end 
            g_checkPedIndex = g_checkPedIndex + 1 
            if g_checkPedIndex > #g_Players then 
                g_checkPedIndex = 1 
            end 
            local player = g_Players[g_checkPedIndex] 
            if not getPedOccupiedVehicle(player) then 
                local vehicle = g_Vehicles[player] 
                if vehicle and isElement(vehicle) and not isPlayerRaceDead(player) then 
                    outputDebugString( "Warping player into vehicle for " .. tostring(getPlayerName(player)) ) 
                    warpPedIntoVehicle( player, vehicle ) 
                    warped = warped + 1 
                end 
            end 
        end 
    end, 
    50,0 
) 
 
That's the code that warps the players back into their vehicles, is inside "race/race_server.lua".