NOTES TO THE CONSOLIDATED FINANCIAL  STATEMENTS  12.  Prepaid operating leases (cont’d) (RMB AND US$ AMOUNTS EXPRESSED IN THOUSANDS, EXCEPT PER SHARE DATA)  As of December 31, 2013, prepaid operating leases with a carrying amount of Rmb 81.1 million (US$13.2 million) (2012:  Rmb 84.4 million) are pledged to secure bank facilities. 13. Goodwill Goodwill represents the excess of costs over fair value of net assets of businesses acquired. Goodwill acquired through business combinations have been allocated to two cash-generating units for impairment  testing as follows: l Yuchai l  Yulin Hotel. Goodwill allocated to Yulin Hotel was fully impaired in 2008. 31.12.2012 31.12.2013 31.12.2013 Rmb’000 Rmb’000 US$’000 Cost At January 1 487,729 457,963 74,829 Additions 8,561 75,610 12,354 Disposal of a subsidiary (38,327) —  —  Disposals —  (12,828) (2,096) At December 31 457,963 520,745 85,087 Accumulated amortization At January 1 88,598 98,781 16,140 Charge for the year 13,148 11,829 1,933 Disposal of a subsidiary (2,965) —  —  Disposals —  (4,473) (731) At December 31 98,781 106,137 17,342 Net carrying amount 359,182 414,608 67,745 Rmb’000 US$’000 Cost At January 1, 2012, December 31, 2012 and December 31, 2013 218,311 35,671 Accumulated impairment At January 1, 2012, December 31, 2012 and December 31, 2013 5,675 927 Net book value At December 31, 2012 and December 31, 2013 212,636 34,744 China Yuchai International Limited | Annual Report 2013 90