The 2005 American Le Mans Series season was the 35th season for the IMSA GT Championship, with it being the seventh under the American Le Mans Series moniker. It was a series for Le Mans Prototypes (LMP) and Grand Touring (GT) race cars divided into 4 classes: LMP1, LMP2, GT1, and GT2. It began March 19, 2005 and ended October 16, 2005 after 10 races.

The schedule change from 2004 to 2005 was minimal, with only one event being added to the existing schedule. The Grand Prix of Atlanta returned once more, once again shortly after the 12 Hours of Sebring.

Overall winner in bold.

Rnd	Circuit	LMP1 Winning Team	LMP2 Winning Team	GT1 Winning Team	GT2 Winning Team	Results
		LMP1 Winning Drivers	LMP2 Winning Drivers	GT1 Winning Drivers	GT2 Winning Drivers
1	Sebring	#1 ADT Champion Racing	#10 Miracle Motorsports	#57 Aston Martin Racing	#31 Petersen/White Lightning	Results
		JJ Lehto Marco Werner Tom Kristensen	Jeff Bucknum Chris McMurry Ian James	Darren Turner David Brabham Stéphane Ortelli	Jörg Bergmeister Patrick Long Lucas Luhr
2	Road Atlanta	#1 ADT Champion Racing	#37 Telesis Intersport Racing	#3 Corvette Racing	#50 Panoz Motorsports	Results
		JJ Lehto Marco Werner	Jon Field Clint Field	Ron Fellows Johnny O'Connell	Bill Auberlen Robin Liddell
3	Mid-Ohio	#16 Dyson Racing	#8 B-K Motorsports†	#3 Corvette Racing	#23 Alex Job Racing	Results
		Butch Leitzinger James Weaver	James Bach Guy Cosmo	Ron Fellows Johnny O'Connell	Timo Bernhard Romain Dumas
4	Lime Rock	#1 ADT Champion Racing	#10 Miracle Motorsports	#4 Corvette Racing	#23 Alex Job Racing	Results
		JJ Lehto Marco Werner	Jeff Bucknum Chris McMurry	Oliver Gavin Olivier Beretta	Timo Bernhard Romain Dumas
5	Infineon	#2 ADT Champion Racing	#37 Intersport Racing	#3 Corvette Racing	#23 Alex Job Racing	Results
		Frank Biela Emanuele Pirro	Clint Field Liz Halliday	Ron Fellows Johnny O'Connell	Timo Bernhard Romain Dumas
6	Portland	#2 ADT Champion Racing	#37 Intersport Racing	#4 Corvette Racing	#23 Alex Job Racing	Results
		Frank Biela Emanuele Pirro	Gregor Fisken Clint Field	Oliver Gavin Olivier Beretta	Timo Bernhard Romain Dumas
7	Road America	#2 ADT Champion Racing	#10 Miracle Motorsports	#4 Corvette Racing	#31 Petersen/White Lightning	Results
		Frank Biela Emanuele Pirro	Jeff Bucknum Chris McMurry	Oliver Gavin Olivier Beretta	Jörg Bergmeister Patrick Long
8	Mosport	#16 Dyson Racing	#37 Intersport Racing	#4 Corvette Racing	#31 Petersen/White Lightning	Results
		Butch Leitzinger James Weaver	Clint Field Liz Halliday	Oliver Gavin Olivier Beretta	Jörg Bergmeister Patrick Long
9	Road Atlanta	#2 ADT Champion Racing	#37 Intersport Racing	#4 Corvette Racing	#31 Petersen/White Lightning	Results
		Frank Biela Emanuele Pirro	Jon Field Clint Field Liz Halliday	Oliver Gavin Olivier Beretta Jan Magnussen	Jörg Bergmeister Patrick Long
10	Laguna Seca	#15 Zytek Engineering	#6 Penske Racing	#4 Corvette Racing	#31 Petersen/White Lightning	Results
		Tom Chilton Hayanari Shimoda	Lucas Luhr Sascha Maassen	Oliver Gavin Olivier Beretta	Jörg Bergmeister Patrick Long
Source:[3]

† - The #8 B-K Motorsports entry failed to finish but completed enough laps to score points.

Points are awarded to the top 10 finishers in the following order:^[4]

• 20-16-13-10-8-6-4-3-2-1

Exceptions were for the 4 Hour Monterey Sports Car Championships was scored in the following order:

• 23-19-16-13-11-9-7-6-5-4

And for the 12 Hours of Sebring and Petit Le Mans which award the top 10 finishers in the following order:

• 26-22-19-16-14-12-10-9-8-7

Cars failing to complete 70% of the winner's distance are not awarded points. Teams only score the points of their highest finishing entry in each race.

Pos	Team	Chassis	Engine	Rd 1	Rd 2	Rd 3	Rd 4	Rd 5	Rd 6	Rd 7	Rd 8	Rd 9	Rd 10	Total
1	ADT Champion Racing	Audi R8	Audi 3.6L Turbo V8	26	20	13	20	20	20	20	16	26	19	200
2	Dyson Racing	MG-Lola EX257	MG (AER) XP20 2.0L Turbo I4	19	16	20	13	16	16	16	20	22	16	174
3	Autocon Motorsports	Riley & Scott Mk III C	Élan 6L8 6.0L V8						10	10		16	9	45
4	Zytek Motorsports	Zytek 04S	Zytek ZG348 3.4L V8			10							23	33

Pos	Team	Chassis	Engine	Rd 1	Rd 2	Rd 3	Rd 4	Rd 5	Rd 6	Rd 7	Rd 8	Rd 9	Rd 10	Total
1	Intersport Racing	Lola B2K/40 Lola B05/40	Judd KV675 3.4L V8 AER P07 2.0L Turbo I4		20	16		20	20		20	26	11	133
2	Miracle Motorsports	Courage C65	AER P07 2.0L Turbo I4	26			20	16		20	16		19	117
3	B-K Motorsports	Courage C65	Mazda R20B 2.0L 3-rotor		16	20		13	16		13	22	16	116
4	Van der Steur Racing	Lola B2K/40	AER P07 2.0L Turbo I4		13		16			16			13	58
5	Penske Racing	Porsche RS Spyder	Porsche MR6 3.4L V8										23	23
6	BAT Competition	Lola B2K/40	AER P14 3.0L V6									19		19

Pos	Team	Chassis	Engine	Rd 1	Rd 2	Rd 3	Rd 4	Rd 5	Rd 6	Rd 7	Rd 8	Rd 9	Rd 10	Total
1	Corvette Racing	Chevrolet Corvette C6.R	Chevrolet 7.0L V8	22	20	20	20	20	20	20	20	26	23	211
2	ACEMCO Motorsports	Saleen S7R	Ford 7.0L V8	16	10	13	13	13		6	13	19	11	114
3	Carsport America	Dodge Viper GTS-R	Dodge 8.0L V10	10	6	6		8	8	10	8	10	9	75
4	Pacific Coast Motorsports	Chevrolet Corvette C5-R	Chevrolet 7.0L V8	12	8	10	8	6	13	8				65
5	Aston Martin Racing	Aston Martin DBR9	Aston Martin 6.0L V12	26								22	16	64

• Note - Although Maserati Corse was allowed to race the non-homologated Maserati MC12, it was not allowed to score championship points.

Pos	Team	Chassis	Engine	Rd 1	Rd 2	Rd 3	Rd 4	Rd 5	Rd 6	Rd 7	Rd 8	Rd 9	Rd 10	Total
1	Petersen/White Lightning	Porsche 911 GT3-RSR	Porsche 3.6L Flat-6	26	13	16	16	16	3	20	20	26	23	179
2	Alex Job Racing	Porsche 911 GT3-RSR	Porsche 3.6L Flat-6		16	20	20	20	20	16	16	22	11	161
3	Flying Lizard Motorsports	Porsche 911 GT3-RSR	Porsche 3.6L Flat-6	19	10	6	13	10	13	13	10	19	13	126
4	BAM!	Porsche 911 GT3-RSR	Porsche 3.6L Flat-6		4	8	2	13	16	10	13	14	16	96
5	J3 Racing	Porsche 911 GT3-RSR	Porsche 3.6L Flat-6	22	6	13	8	6	6	2	8	12	9	92
6	Panoz Motor Sports	Panoz Esperante GT-LM	Ford (Elan) 5.0L V8		20	10	6	8	10	8	4		19	85
7	The Racer's Group (TRG)	Porsche 911 GT3-RSR	Porsche 3.6L Flat-6	16										16
8	IN2 Racing	Porsche 911 GT3-RSR	Porsche 3.6L Flat-6	14										14
9	ZIP Racing	Porsche 911 GT3-R	Porsche 3.6L Flat-6	12										12

• American Le Mans Series homepage
• IMSA Archived ALMS Results and Points^{[permanent dead link‍]}