First of all, batteries and the charging of batteries is a big deal and certainly can be a show stopper. A hybrid electric car would be a better option, for certain, even if the main use was with charging at home.
Next, Bert22306 was correct in his assertions about efficiency and vehicle weight. Most of the problems come from the safety requirements. I would be quite happy to ride in a car that was only as safe as my 1965 Barracuda, or my 1964 Valiant. Both were smaller but much more maneuverable, which is handy for getting out of the way when other folks make mistakes. In fact, I don't think that anybody should be allowed to drive one of those "tanks" that protect them every time they do something dumb. If, as a nation, we accept the theory of evolution, let us not work so hard at thwarting it as we presently do. OK? The courts consistently reward stupidity and general dumbness, and as a result, it looks like we are indeed headed that way. Just when we engineers think that we have made something foolproof, along comes a more foolish fool to prove us wrong.
My 1955 GM PD4104 highway coach with a 6071 direct injection Detroit Diesel averaged 10mpg in its 680,000 mile logbook which translates to 130mpg/ton. You may say that the bus had the aerodynamics of a brick, compared to a car but you would be wrong. It's secret was a full belly pan. A vehicle's major source of drag is between the road and the underside where air shear and turbulence is greatest as the air is trapped and cannot get out of the way the way smoothly the way it can on the outside of a vehicle.
Citroens all had full belly pans. Their wind tunnel featured a conveyor belt so the road effect could actually be measured. Most other manufacturers couldn't be bothered, which I call outright laziness or stupidity. At the time, Mercedes' wind tunnel consisted of 2 large fans in a large open room with the car between them. The Citroen CX diesel had faster acceleration and higher top speed than the Mercedes turbo diesel and better economy than the VW Golf diesel.
As far as safety and weight is concerned you might want to look up the Citroen CX of the '70s again. Again a roomy sedan weighing in at 2800 lbs. designed for safety. It's claim to fame was crashing into a barrier wall at and angle of 60 degrees (imagine the twist) at 60mph (not the the 10mph nonsense) and you could open and close three of the four doors! Citroen was known even in the '30s for filming its cars crashing spectacularly to demonstrate their safety.
Just for reference, the 2012 Fiat 500 weighs in at 2600 lbs.
I owned a Massey Ferguson 35 tractor and a Massey Ferguson 135 at the same time for a few years. The significant difference between these near identical three cylinder diesel engines was that the 35 had pre-combustion chambers and the 35 had direct injection with a swirl chamber in the piston. The direct injection engine would start easily as long as the starter could turn it over. The pre-combustion engine, which had been completely overhauled needed glow plugs and would crank for ages and smoke like crazy at cold temperature before it would start. The fuel economy of the 135 was more than 30% better dragging the same farm implements through the ground. I averaged 1 gal per 2 hours running time.
I also owned a GM PD4104 highway coach with a 6-71 direct injection Detroit Diesel. It also started as long as the starter could barely turn over the engine at the coldest temperatures (using #1 Diesel of course). This 26,000lbs bus always averaged 10mgp or better (in its 680,000 mile logbook)which translates to 130mpg/ton. This mileage is a figure even today's prototype cars have been unable to better. We're talking about a bus built in 1955 by GM. So they know how.
Hardly a conspiracy.
First of all direct injection in dielsels has nothing to do with "better fuel economy." Diesels work by first compressing the air until it gets real hot (20:1 compression or so), and then injecting the diesel, which starts burning spontaenously from the heat. Glow plugs are only used for starting. And having no glow plugs to start, like buses, can be a real problem in cold weather. For buses which leave from a garage, no big deal. For cars, a much bigger deal.
Gasoline engines use spark plugs to get the gasoline to burn. Direct injection is not essential to make that work, so you can avoid the use of the high pressure injector pump.
Mercedes Benz 300SL cars from the mid 1950s had direct injection. Mechanical, of course. Pretty much of a costly nightmarish system, for the owner.
As to weight of cars, a lot of that is caused by the safety regs.
I doubt there are any conspiracies of stupidity or otherwise here.
Watching the snail's pace of incorporating proven designs in the auto industry just makes me shake my head. The auto industry seems to be intent on working on hair-brained schemes instead and compete to be in lock step with their competitors bizarre stylings.
Direct injection for diesel engines first appeared in Detroit diesel engines before WWII. The vast majority of industrial diesels were direct injection by 1967 because of their better efficiency and easier starting. The automotive industry didn't get around to eliminating pre-combustion chambers with their glow plug starting and black exhaust until well into the '90s.
Diesel electric locomotives have been around for over 70 years. Rumor has it that the automotive industry is finally getting around to diesel hybrids that almost double fuel mileage compared to gas electric, some day soon. Why did they even bother with gas electric hybrids?
We hear all kinds of blabber about reducing weight in cars. Consider that the Citroen DS, which hit the market in 1954 had enough room for my 6'4" frame to fit in the front seat and still cross my legs in the back while wearing a hat. With its generous limo sized interior, hydraulic suspension, front wheel drive and aerodynamic body the DS still managed to weigh in at only 2800 lbs, 58 years ago. That weight is hard to beat for even compact cars today. My 2007 Buick Lucerne with less passenger room than the old DS weighs in at over 4,000lbs, despite its generous use of aluminum and the "latest" weight saving technologies. Even its magnetic ride and handling is a far second from the DS's.
Why are they not designing cars that the average American can fit into? Why do they bring the roof down around your ears in the back seats? Why isn't there room in our cars to fit adults comfortably in all their seats any more? It's obvious the industry wants to force us to buy its trucks and SUVs.
A conspiracy of stupidity.
Sure there's been a technology that was just as fitful in its evolution. Just look at the early days of automobile versus horse & buggy. Early autos were the playthings of people with more money than cents. The rank-and-file stuck with the horse & buggy because they couldn't justify the cost of an auto, never mind its growing pains and idiosyncrasies. Not until Henry Ford came along and made the automobile relatively affordable and reliable would the auto industry take off. EV's are no different. Hydrocarbon fuels will have to get very expensive before EV's become attractive. Even if your electricity were free, an IC car is still a better deal for the first 150,000 miles.