Where do you get the idea that electric cars are 3x as efficient? I haven't heard this number before.
Also the idea of "renewable source -> electricity" is conveniently omitting an important step for lots of renewables. That is "heat". Solar panels don't need this, but for example thermal solar (using a working material like molten salt) does.
You haven't heard the number before? Combustion engines are physically limited to a maximum of 40% efficiency. But that is at their peak performance point. That is basically the efficiency a thermal power plant runs on. But with cars, you are often far off the optimal operations point, so the real life efficiency is much lower, real-world efficiencies are below 20%. That is also the reason, hybrid engines save some fuel, as they aim to raise the average efficiency a bit.
Electric engines have efficiencies of about 95%. There are some charging losses and network transmission, but the 60% efficiency needed to be 3x efficient as ICE cars are easy to hit.
Or to calculate the other way around: a Tesla Model 3 uses less than 20kWh/100km. That roughly equivalents to 2l of fuel per 100km. Most cars use 6 to 8l for comparable performance, so the 3x factor checks out well.
The life cycle emissions of an EV are about half those of an ICE. So maybe a 2x factor is better. EV manufacture has a higher environmental cost than ICE.
You're just changing the point you measure the conversion losses at. Yes, electric motors are commonly 90%+ or 95%+. Even really bad ones hit that number.
When an EV is being charged by a natural gas turbine hooked into the electric grid, the efficiency is about the same.
Basically imagine if instead of having an transmission in my regular truck I just coupled my engine to an enormous alternator. Then used the electrical energy to run electric motors driving the wheels. It is in no way more efficient.
Even if you generate energy using oil or natural gas, it helps that the combustion happens in a 55-60% efficient combined cycle power plant rather than a 20-30% efficient car engine.
And of course it enables power generation that is not bound to inefficient combustion - be it hydro, solar PV, wind etc.
Absolutely, it is a step in the right direction. But the small jump in efficiency from say 40% to 55% doesn't really do anything. You've still got a carbon footprint that is non-zero.
Unless you convince society to build zero-carbon electrical generation it's the equivalent of the British calling the American Revolutionary War a victory on their part. The difference is purely political, societal, and cultural. None of which can change the laws of physics.
My observation is United States society simply doesn't want or care about zero carbon electrical generation. Nuclear fission was figured out a long time ago & we basically never built any significant capacity in that regard. Fossil fuels are cheap, which means cheap energy.
Also the idea of "renewable source -> electricity" is conveniently omitting an important step for lots of renewables. That is "heat". Solar panels don't need this, but for example thermal solar (using a working material like molten salt) does.