million, which consist primarily of $40.5 million of personnel and professional fees, $11.5 million of legal costs, $11.8 million of insurance premiums and $7.3 million in other services, software, marketing and overhead costs.
Total SG&A expenses for the year ended December 31, 2021 were $105.4 million, including $4.5 million in litigation accruals. The remaining $100.8 million in SG&A consisted of $49.8 million of personnel and professional fees, $35.4 million of legal fees, $8.6 million of insurance premiums and $7.0 million of other services, software, marketing, and overhead costs.
Research and development (“R&D”) expenses were $107.8 million during the year ended December 31, 2022, which includes $1.8 million of accelerated stock compensation and the impact of $18.4 million received as reimbursement of certain operating costs incurred by the Company between September 1, 2021 and the APA Closing as described in Note 1 — Description of Organization and Business Operations.
Until we began commercial release production of the Endurance, the costs associated with operating the Lordstown, Ohio facility were included in R&D as they related to the design and construction of beta and pre-production vehicles, along with manufacturing readiness. During the year ended December 31, 2022, we incurred $33.3 million in costs associated with the manufacturing facility, which is net of the $18.4 million reimbursement under the APA. The total costs associated with operating the Lordstown, Ohio facility in 2022, included $17.2 million in personnel and professional fees, $7.8 million in freight, $4.5 million in utilities and $3.7 million in other facility and manufacturing costs. The substantial majority of the costs associated with operating the Lordstown, Ohio facility were incurred prior to the sale of the plant to Foxconn on May 11, 2022 (see Note 1). After May 11, 2022, we incurred costs to prepare the manufacturing equipment we continue to own for production. Those manufacturing readiness costs incurred during the third quarter of 2022 totaled $0.8 million and were reported in R&D. Beginning with the fourth quarter of 2022, manufacturing related costs are reported in cost of sales. During the year ended December 31, 2021, we incurred $57.1 million in costs associated with operating the Lordstown facility, including $41.0 million in personnel and professional fees, $7.7 million in utilities, and $8.4 million in other facility operating costs.
Also included in R&D expenses are the prototype components used for part, module or system design testing and validation, as well as full production of beta and pre-production vehicles. For the year ended December 31, 2022, our prototype component costs totaled $22.8 million compared to $104.5 million in 2021. The substantial majority of the 2022 costs represented parts used in the production of pre-production vehicles, and declined as we began purchasing parts for commercial production classified in inventory.
All other R&D expenses totaled $70.0 million for the year ended December 31, 2022, which primarily consisted of $55.2 million of personnel and consulting, $0.9 million of freight, and $13.9 million of other services, software, facilities, and general operations.
Total R&D costs for the year ended December 31, 2021, were $284 million, including $57.1 million associated with operating the Lordstown, Ohio facility and $104.5 million of prototype components. The remaining $122.4 million in R&D consisted of $103.7 million in personnel and consulting, $7.0 million in freight and $11.8 million of other services, software, facilities and general operations.
Impairment of fixed assets totaled $95.6 million during the year ended December 31, 2022, of which $74.8 million took place in the quarter ended September 30, 2022, as described in Note 4. As of December 31, 2022, property, plant, and equipment was reviewed for potential impairment for recoverability by comparing the carrying amount of our asset group to estimated undiscounted future cash flows expected to be generated by the asset group. The fair value was derived from the Company's enterprise value at the time of impairment as we believe it represents the most appropriate fair value of the asset group in accordance with accounting guidance. Additional impairments could occur in future periods and may be significant.
As of December 31, 2022, we reviewed our prepaid GM components and royalties for impairment given that the production volume of the Endurance is not anticipated to exceed 500 units. Therefore, we determined it