SJ X12
The X12 is a series of two-car electric multiple units originally operated by Statens Järnvägar on local trains. Eighteen units were built by Asea Brown Boveri in 1991–94. The X12 is based on the somewhat older X10 but has a higher top speed and an interior adapted for longer journeys. They were fitted with a toilet, galley and two class seating arrangement when entering service. The first and second class both had the same seats although first class had more legroom.
During the later 1990s and 2000s the X12 were put into service by Regional Transport Authorities including Upplands Lokaltrafik who operated three from 1997 to 2003, two were upgraded to X14. Västtrafik also received several several X12 during the early 2000s, they were repainted in Västtrafik colours and fitted with a single class configuration. SJ kept a few to be used on lines in Mälardalen and these received a full retrofit in 2012 that included new toilets, electrical outlets, better seats, handicap toilets, wheelchair ramps and a full repaint to better fit in with the rest of SJs fleet.
During 2021 the X12s in Mälardalen were replaced with newer X50, X52 and ER1. The trains were transferred to Västtrafik service, Transitio who previously kept three unrefurbished scrapped them in 2021.
Units status in January 2026
| Unit | Status | Notes |
| 3190 | Rebuilt to X14 | X14 for Östgötatrafiken, currently X14 3190 for Krösatågen. Previously named Nyköpingen. |
| 3191 | Scrapped in 2021 | Transitio |
| 3192 | Scrapped in 2021 | Transitio |
| 3193 | Scrapped after spare parts picking | Transitio |
| 3194 | In use | Modernized by SJ, leased to Västtrafik. |
| 3195 | In use | Modernized by Västtrafiken |
| 3196 | In use | Modernized by Västtrafiken |
| 3197 | In use | Modernized by Västtrafiken previously named Hubert. |
| 3214 | In use | Modernized by Västtrafiken |
| 3215 | In use | Modernized by Västtrafiken |
| 3216 | In use | Modernized by Västtrafiken |
| 3217 | In use | Modernized by Västtrafiken |
| 3218 | In use | Modernized by Västtrafiken |
| 3219 | In use | Modernized by Västtrafiken |
| 3220 | In use | Modernized by SJ, leased to Västtrafik. |
| 3221 | In use | Modernized by SJ, leased to Västtrafik. |
| 3222 | In use | Modernized by SJ, leased to Västtrafik. |
| 3223 | Rebuilt to X14 | X14 for Östgötatrafiken, currently X14 3223 for Krösatågen. |