The battery charger used to charge the batteries in the car isn't likely to be much more than 80% efficient (that is typical for a switchmode power supply). Batteries don't give back what you put into them either.
Haven't looked at battery chargers in a while. But, my point is I was just comparing car to car efficiency for a rough apples to apples comparison. We can back them all up the line. For example gasoline has to be manufactured in a refining process and that takes energy. It also has to be pumped, transported and distributed (usually through truck tankers on the highway and more than once - I use to drive these) and that takes energy. You also have to pump it into your car - more energy.
Electricty is generally a little easier to handle and distribute with the existing power grid. Overall there is less waste.
It is true that the efficiency of an overall system is the product of all the subsystem efficiencies. For example in a car that burns gasoline we have the engine efficiency, drive train efficiency, chasis efficiency, etc. all subassemblies with their own efficiencies. Multiply all these together and you get the overall efficieny of the car. The 90 to 95 % I cited relates primarily to the engines -so the overall will be a little less when you factor in drive trains, etc. But I purposely neglected distribution to get a better comparison of the vehicles themselves.