Read this before purchasing a used i3

The short answer is buy the newest i3 you can afford.  BMW made continuous improvements over the years, some more significant than others but you will typically be best off purchasing the newest vehicle you can (even if it means saving up for longer).  The AC compressor for example, has had multiple revisions, each less prone to issues than the last.

The i3 came with three different battery capacities, denoted by their amp-hour rating (60 Ah, 90 Ah, and 120 Ah).  Each increase in battery capacity carries a significant increase in value with the 120Ah being the most expensive.  It is recommended to purchase the biggest battery equipped vehicle you can afford.

There was a facelift (refresh, LCI, etc.) in 2018.  The easiest way to differentiate between the original and facelift is the front lights daytime running lights.  Pre-facelift has round lights, post-facelift has horizontal angular lights.  There were a couple other visual changes as well, but the front lights is the fastest way to differentiate the two.

Original models came with DC fast charging as an option.  It wasn’t until 2015 that fast charging became standard, so if you’re looking to purchase a 2013/14, confirm it has fast charging before you purchase it.

Motor mounts have had changes throughout the production run.  The original 2013 model year came with plastic motor mounts that would frequently break.  Sometime in 2014 BMW implemented a reinforced mounting bolt for the motor mount.  This improved the durability but it wasn’t until 2017 that BMW swapped to an even stronger aluminum motor mount.

The original i3 utilized a 3g antenna for internet connectivity.  2017 and newer have a 4g antenna, but the older iDrive systems may incorrectly show 3g in the software (it is still connecting over 4g however).  3g service has since been discontinued in the US, so if you can afford it, it is recommended to purchase a 2017+ model.

late 2017 models also received a new traction control system that is able to update much faster resulting in smoother acceleration and deceleration during low traction (potholes, snow, ice, etc.).  Aggressive regen, particularly in snowy weather can catch people off guard, if you let off the throttle too quickly the rear tires can loose traction.  The new traction control system improves upon this, but it will always be trying to slow the car with regen.

The facelift in 2018 comes with an updated version of iDrive, and an optional S version, along with better motor bearings.  The i3S comes with more power, slightly stiffer suspension, lower ride height, and has slightly wider wheels and tires with fender flares.

2019 saw the second battery upgrade to 120 Ah, and CarPlay became standard.