Nissan hat the e-POWER system where a petrol engine is just used to recharge the battery of your electric car and nothing else. In theory they could run that petrol engine at the sweet spot where it produces the least amount of carbon emissions.

i believe there is also a chinese company which is making such a car, their cars have nearly 1000 miles range.

Diesel-electric engines in trains and tanks worked like that during WW2.