Airliners have gotten far more efficient over the last 40 years, starting with the 757/767. (The 757 design got its start from more efficient engines and a new wing shape.) In fact, efficiency improvements are the primary factor driving new airliner models and sales. At the time of the 757 launch, fuel was 40% of the operating cost of air travel.

Not sure your math checks out. EVs are < 1% of fleet and < 2% of sales in the USA. As you say, cars last 10-20 years and this number is rapidly getting longer. Vehicles older than 16 years are the most-rapidly-growing segment of the US vehicle fleet. The average age of US light passenger vehicles hit 12 years in 2016. In 2020 there will still be 80 million cars on the road that were built 1995 or earlier, none of which were electric or even hybrids. Virtually all of the cars sold this year will still be on the road in 2030, and 98% of them will be combustion powered.