I agree (although I suspect other things may have changed with mass as well to yield the provided result).
However, for now, I believe the goal should be to get everyone over to electric cars, regardless of efficiency.
Unfortunately, the paper provided appears to focus on easily measured parameters (mass) and misses the harder ones (eg. Velocity, Cd, and frontal area). It seems that they're overanalyzing extremely slow speed vehicles that they can probably procure cheaply from China and measure with a scale but they completely miss what well-engineered, practical systems can accomplish. It is all too typical of narrow-minded academic research that we all too often see today in that it provides easy math to impress the professor but the conclusion misses so much and doesn't help anyone.
At such unrealistically slow speeds, of course mass dominates.
If one looks at energy consumption and CO2 and other emissions, one finds that but a small amount of them come from low-speed transportation. A more useful study would attack the large users and producers, not irrelevant ones. That might help us to actually save the planet instead of just winning research grants.
EVs are great. Even the most inefficient EV* uses less energy and produces fewer emissions than the best ICE using renewables and are at worst, about the same with the worst form of electricity generation. Sure, we can tweak things going forward but if the aero shape of the EV is the only turnoff for some (rain drip, visibility, towing, car-top hauling, general aesthetics, etc) I hope someone starts making inefficient EVs if that's what it takes to get them out of their ICE.
