I think the comments might be missing the bigger picture. It might be a few percent improvement dissipation or range: minimal impact to you, say 2 watts per car.
But if they are shipping 800k cars per year that's 1.6 MW off the global power consumption for those new cars.
You're using the wrong units. 1.6MW global power consumption has no meaning on its own. 1.6MW is the power that two sports cars can generate.
Power consumption (e.g. energy) requires time, so 2W per car at 2 hours of daily use would be 4Wh per car per day or about 1460Wh per year per car or 1168MWh for 800k cars.
That's the electricity consumption of ~106 average US households [0].
I think that gives a much better picture of the amount of energy you're talking here.
To an outsider, “4Wh/day” could also be expressed as “167 mW (amortized)”. Wh/day is an idiom. I think it’s strange to claim that it’s the only “right” way of expressing power consumption. For a good many people outside the field, the first thing we do when we see such a figure is convert it back to its SI units so that we can do our calculations within the system that we’re more familiar with (and something like 90% of the world uses SI).
First of all I was talking about power consumption, which is never expressed in MW or kW.
Secondly, mW is also power, not electricity consumption.
4Wh is power consumption (or electricity use if you will). The "per day"-part was just referring to the duration, hence the use of a different unit. I could just as well have used Joules and skip the "day"-part entirely to confuse the reader as to how I arrived at the final figure.
Edit: just to make this even clearer - do the dimensional analysis yourself and see why I used Wh/day. Or to put it differently: what do think is the answer to the question "say a car saves 4Wh of electricity every day. How much electricity does the car save in a year?"
Correct me if I'm wrong, but I'd say it saves 4Wh/d•365d = 4•365 Wh/d•d = 4•365 Wh (or 5.256 MJ if you insist).
> the first thing we do when we see such a figure is convert it back to its SI units so that we can do our calculations within the system that we’re more familiar with
I bet my firstborn that the vast majority of the population will not do that and are not familiar at all with the actual meaning of the figure.
Had I converted the whole shebang into Joules instead and expressed the total energy savings as 5.256 Terajoule I can guarantee that outside the odd physics major no one would be familiar with what kind of energy use we're talking about.
Look at your electricity bill and tell me what it unit it uses.
Your solution still answers the wrong question and even results in a contradiction: the initial statement was "say there's a [power] saving of 2W." Your conclusion would be that there's a power saving of 0.167W, which in incoherent with the initial assumption.
Only if you completely ignore the tune-up and car modding scene.
On the BMW side we have the G-Power G6M V10 Hurricane CS (based on the M6 Coupé), for Mercedes there's the Mansory Black Edition (based on the Mercedes S-class/S 63 AMG), Underground Racing uses the Audi R8 V10 TT for its 1500 HP machine, the Porsche 911 has a 9ff F 97 A-Max incarnation with about 1400HP and the 9ff GT9 V-Max.
The 9ff GTurbo comes in at a mere 1200HP, based on the 911 GT3 and there's more.
So no, in the car enthusiast scene even 1MW is is not uncommon. And that's not using Lamborghinis or Bugattis.
You'd be surprised how many street legal modded M3s, S-class and 911 have 800kW or more max power (at least in Europe).
Edit: shame on me - I forgot the Tesla Model S Plaid. Those have straight up 750kW electric power trains, too.
But if they are shipping 800k cars per year that's 1.6 MW off the global power consumption for those new cars.