If in the past years manufacturers had to cheat on emissions in order to present improvements to performance numbers, then there doesn't seem to be much innovation or the tech has stagnated.
On the other hand, there seems to be lots of room for improvement/innovation on the electric side.
The cheating is rather insignificant when compared to the actual decline in emissions over couple past decades.
Internal combustion engines have become more efficient all the time; there is a lot that has been developed there over the years.
Many of those things, such as the material technology, probably benefit also electric vehicles. Tesla as we know it wouldn't be possible without the pile of innovations done with combustion engine cars.