The BMW i8 was one of the few cars that we have seen make into production fairly true to its concept-alike design, and is certainaly a car that still grabs attention wherever it shows up.
Car Throttle recently checked prices of the i8 on the used market in UK, and it seems that earliest units, three years old are offered for around half of the original price.
"We’ve plucked out this 18,159 mile example for closer inspection. It’s up for a little over £60k - £63,950"
2015 BMW i8 Concept
About £60,000 (≈$79,000) is still a lot. New is listed from around £106,000 0 so retaining about 55% of its value.
In the US, a quick survey of some ~200 used copies landed a range of $75,000 to $105,000 (removing the extreme outliers one often finds), with the average price around $89,000. That is a stronger retention rate of about 67% for older i8s.
We should note, that initially when BMW was production constrained, brand-new (and used) i8s were often sold with a significant premium over MSRP. So the movement over the past 18 months is more significant than the percentages alone.
Truthfully, losing 55-66% of value in three years isn't a surprising result in the high-end of the market, and could be growing now in anticipation of newer (and topless) models.
source: Car Throttle