Maybe the answer is a logistics issue. Something like automatically replaced batteries, done at stations much like or repurposed gas stations where depleted batteries are removed and recharged batteries are installed in the time it takes to fill a gas tank.
Tesla already has (had?) a battery-swap station at Harris Ranch, CA. However, it rarely gets (got?) used. I'm saying it this way because I'm not sure it's even open any more. There was a Supercharger right outside, and most folks opted to simply spend the 1/2 hour charging the car, stretch their legs, go to the bathroom, etc. rather than get the 90-second battery swap.
It's not a big deal, stopping every 3-4 hours - Most of us do that in our gas cars, too. It's just a different mindset than we're all used to with a piston-pounder.
Likely much easier to have/rent a generator on a mini trailer which can be towed by the car. Think of it as an on demand hybrid power source. No need to carry it majority of the time; just hook up when you need longer range, forgot to charge the car....
You would need a fairly sizable generator. Something similar to this exists in the BMW i3 REx (Range Extender) - There's a gas engine (a BMW motorcycle engine) that fires up when the battery hits 5%-ish and drives a genset to make electricity to go farther. However, once the battery is fully depleted, it can't give you the full amount of power you'd need for all situations - If you start driving up a mountain on the interstate, you're going to regret it. In fact, you may not be able to maintain a normal highway speed (75) even on relatively level ground. To get that amount of power, you need a car-sized engine, and carrying around that much extra weight kind of defeats the purpose.
Advertised battery range for electric cars reminds me of advertised max cruise airspeeds for piston GA aircraft back in the good ol' days. Achievable only if one is pointed somewhat downhill.
It's actually not that difficult to exceed them by a significant margin (20% or more), but as you note, it's dependent on an awful lot of variables, many of which ICE vehicles are also susceptible to, but aren't noticed so much when range is usually 350+ miles.
(What's the best thing about a Tesla battery pack fire in winter? Underfloor heat

)
I would guess Tesla is achieving increased range with perhaps larger capacity battery packs, steadily improving software management of the charge/discharge cycle, lighter weight of the Model 3 car, an effort to reduce the number of Wh/mile, and maybe a way to more consistently use all of the available battery (down to 1% charge?) without inducing repeated range-anxiety pucker-factor in the owners? Nothing frightens a guy more than not being able to "go the distance".
They've been quite successful at increasing the efficiency of the Model 3 - The drag coefficient is also very low. The owners I know are getting more than 4 miles/kWh. (or less than 250 Wh/mi) Impressive.
Back on the efficiency of batteries, you have to also consider the energy lost in the charging and discharging cycle. Most batteries are capable of discharging between 60 to 70% of the energy put into them. So yes the electric motor may have 90% thermal efficiency, but the batteries do not.
Battery * Motor efficiency is running around 65-70%, yes.
So when we consider the overall efficiency of an electric system, and the potential "greeness" you have an entire energy chain to consider. With an ICE it is essentially one step, fuel to work. Current engines range from 30 to 40 % efficient in that conversion. Now an electric vehicle has four potential points of energy loss ( at least). Initial generation, transmission to use point (power lines etc), charging and discharging the battery, and finally the electric motor. This example assumes that the initial energy refinement and transport to where the fuel is converted to the power source is similar. Here that would be the gas station or power plant. For electric people have to remember the charge needs to come from somewhere.
For gasoline vehicles, the cycle pretty much goes extraction, transportation (of crude), refining, transportation (again, of gasoline) to a terminal, transportation to the station (the least efficient transportation step, since it's generally done via truck in small amounts), and of course pumping at each stage.
For electric vehicles, it really depends on the power mix. Coal, nuclear, natural gas, hydro, wind, solar, and the lesser-used methods all have a different cost, but the advantage is in transportation - There are line losses and transforming losses, but the overall process is pretty efficient.
The key is, even with 100% Coal (the worst of the above), it's still a little in favor of the electric car. And while the grid keeps getting cleaner and in turn doing the same for electric cars, a gas car's best day is the day you drive it off the lot.
Personally, I'm content with the current petro model for transportation except for its susceptibility to price spikes. I think $2 a gallon for gas is a good price for most. $3 a gallon is getting too expensive IMHO and really makes me consider buying electric.
I swear, someone has it out for me. I buy a plug-in hybrid and the gas prices go down 25% in the next 4 months, I buy a gasser and they go up 20% in the next 4 months! I can't win!
We have a municipal electric company here, a year or two ago they had "special" running where you could buy a Nissan Leaf brand new for about $12000, and they would give you a high speed charger that they could control for about $300. You had to pay to get it installed, about another $200 to $300 bucks. I almost did it but, I have enough cars and didn't want to have to deal with another. That car had about a 200 mile range IIRC, and would have served about 90% of my driving needs.
Nissan Leaf a couple years ago would have only had something like 72 mile range. Still works for 90% of driving needs, but really sucks hard on that last 10%!
To your point about efficiency, I used to feel the same way as you do about it, until I started looking at it. My cost per kwh for charging a car, worst case, today, is 12.5 cents per kwh. The model 3 long range has a 75 kwh battery and can go, supposedly, 310 miles on that, fully charged, I don't know if the battery fully discharges or not, but I assume that is figured into the range. So if I assume the charger is 80% efficient (this number should be pretty conservative from what I read), it will take 94 kwh to charge my battery. If I do the math, it will take $11.75 worth of electricity to charge my car. Versus a 30 mpg car (which again is probably conservative for a comparable car that can go 0 to 60 in 5.1 seconds like the model 3) which would use 10 gallons of $2.90/gallon gas ( current price near me) it's less than half to run the electric car. It's hands down more energy efficient as the price I pay has all the electric grid inefficiencies built into it.
Yep. I would only add that charging via 240V is generally in the 85%-90% efficient range (75-80% for 120V). The Model 3 has a battery pack just a tad over 80kWh, with about 75 usable so your calculations are right in the ballpark.
I find in general that the gas car costs about 3x per mile what the electric one does, and that's not counting maintenance, which is much more in favor of the EV.
Gasoline EPA numbers are the same type of dream numbers, but you have to set a basis somewhere and supposedly they are "scientific".
Yep. It's a consistent methodology anyway. If you want real dream numbers, the NEDC can give them to you.
The reason I said I was "impressed" in that prior post is because
I figured they would be toast long before this.
Elon Musk makes some rather outlandish, unbelievable statements sometimes, but his ability to execute on them (timeframe notwithstanding) makes betting against him a bad idea.
But I think my experience is also the outcome for millions of our workers. They will never be able to afford these expensive green toy baubles, and most of them are probably doing a version of what I do, but not by choice - driving a well used gasoline engine Toyota Corroded because they have to get to their jobs so they can feed their families and pay their taxes
Most of our "workers" can't afford to buy any new cars. Luckily, some of the non-Tesla electrics are depreciating so quickly early on that they'll be able to afford to buy a commuter EV that's newer than an otherwise-equivalent gas car, and save on operation costs.