In Tesla's environmental impact report [1], they estimate the average car in the US is driven 12,000miles/year for 17 years before it's scrapped. They amortize over this period for their lifecycle C02 impact of a Model 3. From my own research, this number is a good guess, though it's region dependant. This doesn't match the OP which claims Tesla's are only engineered to last 6 years before expensive maintenance.

[1] https://www.tesla.com/ns_videos/2019-tesla-impact-report.pdf (page 8)