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      08-15-2020, 11:26 AM   #13
MolarBear
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Drives: BMW i8 LCI
Join Date: Jul 2020
Location: UK

iTrader: (0)

A few more observations which I found interesting on how it appears the drive modes work (I have a long motorway commute at 70mph so it gave me something to play with whilst on cruise control):

Sport - battery < 71.5% - Engine powers both the car and charges the battery - manual change to 6th gear. Consumption - 20mpg. Charges at the rate of 1% every 0.5 miles so 2% a minute at 70mph.

Sport - battery stops charging at 71.5%. Consumption goes to 39-40mpg. Clearly the small starter motor has stopped the dyno / charging which appears to take 20mpg off the consumption just to charge.

Comfort - cruise control. Consumption goes to 48-49mpg. Power distribution shows petrol engine only and does not show any battery / electric motor contribution. Despite the display showing no electrical motor use, the battery still depletes at a rate of around 1% every 3-4 miles (I think). Clearly in comfort mode there is a little electrical contribution (perhaps it just helps with any loads to help the petrol engine maintain the speed). However these small amount of battery power seems to stretch consumption by another 8-9mpg. I'm not sure what the difference is between sport mode in 6th gear and comfort mode (which presumably also sticks in 6th gear) apart from a minimal battery charge (which seems to only be consuming 0.25% a mile or so). Clearly something is eating up 9mpg in the modes and surely it can't just be the minimal amount to maintain the battery?

None of this is relevant at all for when doing anything fun or spirited of course, just interesting for me to see as a new owner what exactly is going on underneath the hood and how the drive train works !