All this while, I thought the monthly bills are calculated based on: Consumption - Export , and tariffs are applied accordingly after that.

If it's like someone said, where the consumption is charged according to the tariffs and export is paid using highest tariff, macam give and take kan?

If your reason for saying ev is not environmentally good is due to batteries, I can still agree.
But if you say it's because of "dirty electricity", I have to disagree.

Our power plants are more efficient than an ICE car can ever be. It means, less wastage of energy from power plant compared to ICE cars. Power plants recover the heat from flue gas by having a waste heat boiler/recovery/heater, whereas in cars you actually need to spend energy (radiator fan) to remove excess heat from engine.

Let's not mention how ICE cars require petrol and diesel - something that requires energy to produce.
Also, fuels need to be distributed to petrol stations around the country by road tankers, further consuming energy.

Could you do this non-science student a favour by explaining why electricity transmission is more dirty than hydrocarbon fuel distribution from refinery to individual petrol stations using road tankers?

Possible, but I think it also depends on how the biofuel raw materials are sourced. If forests are cleared to plant crops like corns etc to produce biofuels, its environmental impacts may not be better than the impact from using fossil fuels.

As for the ways to minimize energy wastage in ICE cars, I think nobody will invest anything for it as 20 years from now many countries will outlaw the sale of new ICE cars.

Why cannot compare, since I was comparing the environmental impact of ICE vs EV in terms of carbon footprint?

The question is, battery impact on environment aside, are EVs cleaner than ICE ? Keyword is cleaner, not clean.