coleafrado wrote: ↑
Wed May 27, 2020 4:56 pm
Hate to say this, but saving 3 or even 30 pounds on a 3500 pound road car is not going to be remotely measurable in terms of efficiency.
I'm well past twice that 30 pound savings (the battery alone was 15 pounds). In terms of
power/weight ratio, every 1% drop in weight equates to an 'effective' 1% increase in power.
Also, 30 pounds of that weight reduction being rotating, is typically counted as at least double.
So my ~77 pounds of weight reduction (so far, more to go) comes to more than a 2% reduction,
then doubling the rotating weight part of that gives me ~107 pounds, or right at 3%. Increasing
the power (107hp) by that gives you 110.3hp 'effective'.
I agree that efficiency improvements of that magnitude won't show up on the dash meter (not enough precision there). Nor does it affect the cost to operate to any significant degree (it's already just 2-3 cents per mile). But having 'effectively' 3% more power could be noticeable. Running a zero-to-sixty calculator using curb weight (3256) and the above weight savings yields nearly a quarter second improvement (9.787 seconds to 9.545). Adding in the driver's weight doesn't change that improvement by much (0.242 to 0.239).
Of course every vehicle owner has different priorities as to what about their car is important. So I get that not everyone cares about a quarter-second better zero-to-60 time. And keep in mind that's just one benefit of weight reduction. For sure, lighter wheels/tires help with handling (unsprung mass reduction).
Thanks for your feedback.