Unaudited Condensed Consolidated Statements Of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
TOTAL REVENUE	$ 6,552.1	$ 6,690.4
TOTAL COST OF SALES	5,341.0	5,470.5
TOTAL GROSS PROFIT	1,211.1	1,219.9
AUTONATION FINANCE INCOME	9.4	0.1
Selling, general, and administrative expenses	842.2	821.9
Depreciation and amortization	63.0	61.8
Other expense, net	1.0	0.3
OPERATING INCOME	314.3	336.0
Non-operating income (expense) items:
Floorplan interest expense	(41.8)	(46.5)
Other interest expense	(48.0)	(42.3)
Other income (loss), net	51.2	(13.2)
INCOME BEFORE INCOME TAXES	275.7	234.0
Income tax provision	70.3	58.5
NET INCOME	$ 205.4	$ 175.5
BASIC EARNINGS PER SHARE:
Earnings per share, basic (in dollars per share)	$ 5.92	$ 4.50
Weighted average common shares outstanding (in shares)	34.7	39.0
DILUTED EARNINGS PER SHARE:
Earnings per share, diluted (in dollars per share)	$ 5.85	$ 4.45
Weighted average common shares outstanding (in shares)	35.1	39.4
COMMON SHARES OUTSTANDING, net of treasury stock, at period end (in shares)	33.9	37.9
New vehicle
TOTAL REVENUE	$ 3,011.0	$ 3,248.1
TOTAL COST OF SALES	2,866.5	3,073.2
TOTAL GROSS PROFIT	144.5	174.9
Used vehicle
TOTAL REVENUE	1,963.8	1,922.4
TOTAL COST OF SALES	1,842.4	1,797.9
TOTAL GROSS PROFIT	121.4	124.5
Parts and service
TOTAL REVENUE	1,220.9	1,164.0
TOTAL COST OF SALES	627.5	596.3
TOTAL GROSS PROFIT	593.4	567.7
Finance and insurance, net
TOTAL REVENUE	352.0	352.5
TOTAL GROSS PROFIT	352.0	352.5
Other
TOTAL REVENUE	4.4	3.4
TOTAL COST OF SALES	4.6	3.1
TOTAL GROSS PROFIT	$ (0.2)	$ 0.3