One reasonable way to look at efficiency is to take a car that has electric, diesel and petrol engined equivalents with similar power output and compare their energy consumption. The new WLTP test ratings have a lot less re-gen capability for electric cars with the higher speeds used in the test, so the extra energy to compensate for the higher weight of the equivalent electric car will be somewhat balanced out by the re-gen.
An eGolf on the WLTP cycle is rated at 13.2kWh/100km with 100kW maximum power, with test distance of 23.5km over 30 minutes, a total of 11.17MJ of energy used equivalent to 0.330 litres of petrol (33.9MJ per litre / 1.40 litres/100km / 202mpg) or 0.292 litres of diesel (38.1MJ per litre / 1.24 litres/100km / 228mpg). This represents the most efficient use of power to travel a given distance for the car model.
I doubt any 100kW / 135bhp petrol or diesel Golf on the new WLTP cycle (consumptions typically 15 to 20% worse than NEDC) will average any better than 50mpg for petrol or 57mpg diesel, which represents consumptions for an average 25% engine efficiency.
Surely fuel energy efficiency comparison is a red hearing, you're getting hung up on details that don't apply in the real world? The world needs to move to clean and renewable energy, electricity can fulfil this requirement, fossil fuels can't.
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The comparison is relevant, as it gives the current energy usage patterns and infrastructure requirements, which will need to be substituted for in an alternative energy future and cost-benefit analysis should take place to make the right decisions at the right time, including the optimum investment levels (which will in the hundreds of billions of pounds).
I still think EV's are a fad - short term response to a social-media fueled public. Long term affects on planet (resource and supporting infrastructure) will be catastrophic.
Add in the reality check that only approx 3% +/-(depending what your source is) of the population globally can afford an EV of sorts, and the populations in places where you need to reduce emissions are unable to afford to buy a magazine to look at an article about EV's, let alone consider purchasing one, you have a massive conundrum.
As someone highlighted esrlier, UK would need 20+ Hinkleys to cope with local grid demands, and the development of small, clean burn powerful IC units was/is on the up. You also have mass unemployment (not just manufacture but maintainance of cars with i:c engines), and a massive dearth of electronic auto engineers to maintain the washing machine motor attached to each wheel...
Short-sighted, bonkers thinking all round.
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