[FormulaLosAngeles]

The most efficient small Combustion engine is at the university of Wisconsin, where gasoline is thrown down the throat of a direct injection diesel with 45% EGR, resulting in low particulate and low emissions avoiding a catalytic convertor or ammonia treatment. This more matches the crude oil refining fractions, and would be a possible fix for all those recalled diesel cars parked in the desert. Engine weight to power is obviously heavier than pure gasoline conventional engines. This rude formula attemps to capture these tradeoffs. Similarly a Tesla is available with heavier battery packs for long range, same trade off.
a recent thread here "Total Power efficiency between a Hybrid and EV? Who wins?" reflects the cradle to grave analysis, although it depends on EPA kw per mile and some complexity. In early 1990 I went to see Paul Macrready talk at the Ontario CA Electric vehicle association, to razz him about my calcs that greater CO etc came from electrics than IC, but the first think he told us was a rough calc that said the samething! which took the wind out of room full of EV zealots, but then the speech move on to details of EV-1 and the mania went on to todays EV mania, Wherein it is complex to know how each additional pound damages efficiency because it depends on the driving cycle, let alone the cradle to grave analysis that might include the concrete CO for the foundation of the wind generator...
This is why I came up with payload fraction times range, it captures tradeoffs and reflects utility. It depends on driving cycle but could be matched to EPA city versus highway or the average of both by fuel tank size. Battery pack utilization versus pack longevity is variable. Definition of empty weight and gross weight is variable too, Tesla has no spare tire, and if you add more brakes and stiffer suspension gross weight allowable can go up until you cannot climb a hill. So maybe a hill steepness for a length of time at max gross should be part of EPA numbers. In anycase it gets too complex for anyone to have enough time to debate the truth, similar to data revisions of employment, inflation, money supply, GAAP accounting. So this rude version had its origin in the MV 22 Osprey versus a plain old helicopter, where the expensive and exotic is sold as better, but is so inefficient that people had to travel on roads and get blown up by IEDs.