There’s no reduction in performance (i.e horsepower) as the car ages.
intuitively you would expect there to be and, when I made the comment, I wondered if it had been measured on cars,
so I'd like to see someone who has checked their 0-60mph at 60K miles versus infancy
googling a bit on battery chemistry you can see articles like this, which discuss irreversible increase in cell resistance, caused by heat (as would occur with rapid discharge/acceleration) which, won't reduce the capacity, but will mean the maximum sustained current the cell can deliver (ie torque/amps) declines.
https://www.nature.com/articles/srep12967
Overview of the temperature effect on aging rates
From the above analysis, it was found that higher temperature will increase the degradation rates of all the components in a LiB and this is consistence with the work of Thomas et al.10.Careful examination of the Tables inserted in the Figures that show the degradation as a percentage of each component in a LiB reveals that temperature has the largest impact on the degradation rate of the Warburg element with cycling and followed by the cell impedance. The degradation rate of the charge transfer rate is less impacted by the operating temperature for the temperature operating range considered here.
As the operating temperature of LiB changes from 25 to 55 °C, the degradation rate of maximum charge storage after 260 cycles is found to increase from 4.22% to 13.24%. At the component level, for the same change in the operating temperature, the degradation rate of the Warburg element resistance after 260 cycles increases from 49.40% and 584.07% (Fig. 10) which is the highest change; and that for the cell impedance ranks second, increasing from 33.64% to 93.29% (Fig. 8). As for the charge transfer rate, the change in its degradation rate decreases from 68.64% to 56.19% (Fig. 7).
From the above analysis, it was found that higher temperature will increase the degradation rates of all the components in a LiB and this is consistence with the work of Thomas et al.10.Careful examination of the Tables inserted in the Figures that show the degradation as a percentage of each component in a LiB reveals that temperature has the largest impact on the degradation rate of the Warburg element with cycling and followed by the cell impedance. The degradation rate of the charge transfer rate is less impacted by the operating temperature for the temperature operating range considered here.
As the operating temperature of LiB changes from 25 to 55 °C, the degradation rate of maximum charge storage after 260 cycles is found to increase from 4.22% to 13.24%. At the component level, for the same change in the operating temperature, the degradation rate of the Warburg element resistance after 260 cycles increases from 49.40% and 584.07% (Fig. 10) which is the highest change; and that for the cell impedance ranks second, increasing from 33.64% to 93.29% (Fig. 8). As for the charge transfer rate, the change in its degradation rate decreases from 68.64% to 56.19% (Fig. 7).
or (now I understand teminology/what i'm looking for)
https://batteryuniversity.com/learn/article/rising_internal_resistance
Capacity alone is of limited use if the pack cannot deliver the stored energy effectively; a battery also needs low internal resistance. Measured in milliohms (mΩ), resistance is the gatekeeper of the battery; the lower the resistance, the less restriction the pack encounters. This is especially important in heavy loads such as power tools and electric powertrains. High resistance causes the battery to heat up and the voltage to drop under load, triggering an early shutdown. Figure 1 illustrates a battery with low internal resistance in the form of a free-flowing tap against a battery with elevated resistance in which the tap is restricted.