v3.20.4
Property
 12 Months Ended
Dec. 31, 2020
Property, Plant and Equipment, Net [Abstract]  
Property Property
Estimated Useful Lives in YearsDecember 31, 2020December 31, 2019
Land$1,339 $1,302 
Buildings and improvements
5-40
9,671 9,705 
Machinery and equipment
3-27
30,013 29,814 
Special tools
1-13
20,851 23,586 
Construction in progress3,581 3,042 
Total property65,455 67,449 
Less: accumulated depreciation(27,823)(28,699)
Total property, net$37,632 $38,750 

The amount of capitalized software included in Property, net was $1.3 billion at December 31, 2020 and 2019. The amount of interest capitalized and excluded from Automotive interest expense related to Property, net was insignificant in the years ended December 31, 2020, 2019 and 2018.
Years Ended December 31,
202020192018
Depreciation and amortization expense$5,354 $6,541 $5,347 
Impairment charges$86 $7 $466 
Capitalized software amortization expense(a)$457 $452 $424 
__________
(a)    Included in depreciation and amortization expense.