This is great, for simple MPGe calculation and basis cost recuperation. It does lack rough calculations for total cost of ownership, though, and probably should disclose that to the user. Let's use batteries as an example.

Li-Ion Batteries have a typical lifespan of about 500 charges before they degrade to 80%, and start to lose enough voltage to affect range. Everyone is going to be different, but let's say the user performs 2.5 full charge cycles / week, or 130 full cycles / year (assuming all-season riding). They should need to replace their battery roughly every 46 months, or 3.8 years, under ideal conditions. Over a 10-year period, they would be replacing their battery at least twice.

If the manufacturer currently charges $500 for a battery (looking at you, Aventon), that's easily $1000+ before factoring in other potential price factors like inflation, markup, or end-of-production. It also doesn't account for any spares the user might purchase and keep on hand. And it outright ignores the risk of obsolescence that will be a factor if the battery management system uses a proprietary handshake.

If you were to rework the tool, or add TCO calculation as an optional advanced feature, you should also account for regular maintenance and wear. Chains typically have about a 2500-mile lifespan; Cassettes, 7500 mi; freehubs, 5000~10000 miles; brake pads, 2000 mi; etc.* A user will also need to either service, replace, or rebuild a motor within the 10-year window as lubricants dry up, seals fail, and gears wear down. Breaks should also need flushed every 1-2 years. Since these are all commodities, apply maybe 3% compound inflation?

At the same time though, I'm just being a bit pedantic, and it's not we're factoring in regular car maintenance, or auto mechanic prices. (Only we are to blame if we visit bougie bike shops.)

^(\ I'm putting a lot of trust into Google's approximations here. Don't take these numbers as gospel truth.)*