mysql> select mod_eisen from transporte order by id desc limit 2;
+-----------+
| mod_eisen |
+-----------+
|         1 |
|       0.1 |
+-----------+
2 rows in set (0.00 sec)

mysql> select sum(mod_eisen) from transporte order by id desc limit 2;
+-----------------+
| sum(mod_eisen)  |
+-----------------+
| 31354.100000001 |
+-----------------+
1 row in set (0.00 sec)