Sorry Am_Fear_Liath_Mor but your analysis is quite poor. You clearly need more reliable sources of information.

You get the energy content of a barrel of oil about right at 1 bpd = 1.7 MWhrs. What you missed is that you use it assuming that the vehicles are 100% efficient. Simple fact is that a gasoline engine has a theoretical maximum efficiency of roughly 20%. And it is all downhill from there. Bearings aren't perfect. Out of millions of cars how many are perfectly maintained. Then apply that to an engine in a vehicle which spends time idling, using gasoline and returning nothing (efficiency of 0% for energy expended), poor driving habits, etcetera, and there is no bottom end of how inefficient a car can be. A fair working estimate might be that in actual use gasoline powered vehicles actually only use 5% of the energy stored in gasoline actually moving people and products. Already your estimate is twenty times higher than it should be.

Second, electrical systems are not actually overloaded when you consider a typical 24 hour period. Fact is most power plants dump power through resister banks just to keep capacity available. Power plants are set up to run at near full power and throttling them back is problematic. Typically power is shared and entire generation units are put on or off line. There is typically a large rise in electricity used in the morning which tapers off rapidly mid morning and then a large spike in the afternoon which tapers off as night comes on and people start to go to bed.

The key here is that the entire system is designed for maximum load. A maximum load which is easily accommodated. Your need to find a time it was not, Houston during a single rare event, highlights that the vast majority of the time the power is on and working quite well. The reason the situation in Houston was shocking was because electrical generation has become so reliable that its short term failure is a novelty.

The grid is designed for the maximum load and the power plants are designed to run most efficiently at near maximum load. Typically 80%. Most modern electrical plants are getting real world efficiency of better than 30% from the coal or gas used. Nuclear power plants are actually less efficient.

What your missing here is that the charging load for vehicles can be shifted to normal low-load times. This was done in the 40s for electric water heaters. In effect we get a certain amount of power for free because there is less need to start up and shut down units. The end result is an overall increase in the efficiency of electrical power generation because there would be less need to throttle back the generation plants or dump power.

In effect there will be little need to build new electrical power plants because what we have doesn't run at designed output much of the time.

The final point is that major power lines do not use copper. They use conductors composed of a combination of aluminum and steel. But here again, there is not going to be any great need to string more power lines because the lines we have are not running anywhere near capacity most of the time. There are a few isolated choke points where lines are near capacity most of the time but these choke points are a result of commercial advantage and land use issues, not a lack of resources.

Bottom line here is that electric vehicles are entirely practical with the only real issues being the battery capacity and available charging stations. The later point being a non-issue if the vehicles are set up to simply plug into a standard 15/20A receptacle. The trade-off is between more specialized charging stations that will recharge a battery bank quickly, an hour or two, or a standard plug that will do the same thing more slowly, four to eight hours. The Israeli model of simply exchanging a standard modular battery bank works around many of these issues.

In many ways the shift over a few decades to majority of vehicles being electric will be less traumatic than what happened in the 70s when the blow dryer suddenly, in a matter of a couple of months, became a fixture and daily use item in US homes. In effect fifty million people got up one morning and plugged in a 1000 watt space heater for ten minutes. Farah Fawcett and Peter Frampton, with their blowdried hairstyles, had a profound effect on the US power system.

Electric cars, which will take over the market over the next couple of decades, aren't going to be a huge problem for the power systems we have now. Even less so if we get rid of the structure and engineering that is a throwback to technology of the 40s. Which is made possible by oil we aren't paying full freight for and coal which is dirt-cheap.