[milanosie]

Untested, modify it to your liking to return 0 if dis > 10

pawn Code:

public GetClosestVehicleFromPlayer(playerid)
{
    new Float:dis = 99999999.0;
    new veh = -1;
    new Float:x, Float:y, Float:z;
    GetPlayerPos(playerid, x, y, z);
    for(new i = 1; i < MAX_VEHICLES; i++)
    {
        new Float:distance = GetVehicleDistanceFromPoint(i, x, y, z);
        if(distance < dis)
        {
            dis = distance;
            veh = i;
        }
    }
    return veh;
}