My understanding is that EVs are still usually a net win because
1. Power plants can benefit from economies of scale that individual cars cannot, making a gas power plant powering EVs better than individual cars running on gas.
2. As others have said, it is easier to upgrade power plants than all cars on the road.
Power plants are similar in terms of cost and time consuming to upgrade. There are around 30 million cars in the uk. Assuming an average electric car cost of £20,000 that equates to £600 billion and cars tend to be replaced every 15 years (average car age is 8 years). A powerplant costs about £2 for every Watt installed and the uk needs about 100GW or around £200 billion. A typical large scale nuclear or wind project can take 5 to 15 years to complete but on average a powerplant can last 50 years.
A better argument is that in some countries already a large proportion of electricity comes from renewable sources such as hydroelectric in Norway. Sadly this doesn't translate to the whole world: China is mostly powered by coal.
Well, gasoline also has "transmission losses": it takes energy to move large amounts of oil to refineries, then to fuel stations. Such energy is usually also fossil fuel based.