What are the differences between a [model year] and a [model year]?

There are many differences, both major and minor, between various model years.  To date, no comprehensive list exists which details all of the changes; to list them all is beyond the scope of this FAQ.  A few of the high points are:

1990

• Inagural model year of the DSM.
• Pop-up headlights.
• Some high-end models had wheel covers.
• Mix of EPROM and Non-EPROM ECU's
• Front brakes change during the model year.
• 1.8L models have the 4G37 engine, all others have the 4G63 engine.

1991

• ECU changes mean that 1991+ ECUs don't operate the 1990 tachometer correctly.
• Most ECUs had EPROMs.
• First model year with ABS available. ABS not available with limited-slip differential (LSD).
• All high-end models had alloy or mesh wheels.
• First year of the Galant VR-4 - 2000 sold in the American market.

1992

• Non-popup headlights introduced on all models.
• The first AWD Lasers were introduced.
• Few (or no) ECUs have EPROMs.
• ABS now available with LSD.
• The engine changes from the 6-bolt version to the 7-bolt version in April.
• Second and final year of the Galant VR-4 - 1000 sold in the American market.
• The last year of the Dodge 2000GTX.

1993

• "Big brake" 2-piston front calipers become standard on turbo models.
• 7-bolt engines are now standard.
• No ECUs have EPROMs.
• Diamond-Star Motors ceases to exist.

1994

• All cars built to California emissions standards - there are no "Federal" cars.
• The last year of the 1G car and the 1.8L NT models.
• The last year of the Plymouth Laser.

1995

• The inagural year of the 2G DSM.
• Significant changes to the engine, body, and electronics.
• New transmissions.
• All ECUs have EPROMs.
• Non-turbo models are based on the Chrysler 420A engine instead of the Mitsubishi 4G63 engine.
• OBD-II becomes standard on DSMs, along with two oxygen sensors.
• Mitsubishi begins using some substandard crankshafts, leading to crank walk on some 2G cars.

1996

• The first year of the convertible Spyder.
• The Mitsubishi 4G64 engine is offered, in the Spyder models only.
• ECUs stop having EPROMs.

1997

• Additional body changes from the 1995/1996 models.
• Minor changes to the ECU code.

1998

• Minor changes to the ECU code.
• After many years, Mitsubishi finally issues a recall on the AWD DSM transfer case.

1999

• The last year of the 2G car, and of the 4G63/AWD DSM platform.
• The last year of the Eagle Talon. Chrysler drops the Eagle marque.

2000+

• 2000 - The first year of the 3G Eclipse.
• 2002 - The first year of the Lancer (non-Evolution) in the United States and Canada.
• 2003 - The first year of the Lancer Evolution in the U.S.A.
• 2004? - The first year of the Lancer Evolution in Canada?

A photo gallery comprising 100+ images is also available.

Also, for those who are curious (or just nostalgic), Tim Tate has completed the process of immortalizing the original USA dealer brochures for every year, make and model of DSM. Check it out!

For more information on the different model years, it is best to either read the archives (for general information) or to research specific components, as described in 'Has anybody installed a [component] on a [DSM]?'.

There is a page here that has a discussion on the "best" model year of DSM. There is also a page which details the differences between the 1990 engine and the 1993 engine - See this Engine Upgrades page for more detail.

For those looking for ECU-specific information across the various years, please refer to the Technomotive's Sept. 8 issue of The Diagnostic Port.