Can anyone please help make these sentences sound more natural (if necessary)? Many thanks!

- The amount of added sugar in dark chocolate is less than that found in white chocolate.
- Dark chocolate has less added sugar than white chocolate.
- Organic oranges contain 30% more vitamin C than those grown conventionally.
- Organic oranges have 30% more vitamin C than conventional ones.
- Cars today are much more fuel-efficient than those manufactured in 1990.
- Cars today are way more fuel-efficient than the ones from 1990.
- The President's salary is 25 times higher than that earned by the average citizen.
- The President's salary is 25 times higher than the average citizen's.

Question

Can anyone please help make these sentences sound more natural (if necessary)? Many thanks!

- The amount of added sugar in dark chocolate is less than that found in white chocolate.
- Dark chocolate has less added sugar than white chocolate.
- Organic oranges contain 30% more vitamin C than those grown conventionally.
- Organic oranges have 30% more vitamin C than conventional ones.
- Cars today are much more fuel-efficient than those manufactured in 1990.
- Cars today are way more fuel-efficient than the ones from 1990.
- The President's salary is 25 times higher than that earned by the average citizen.
- The President's salary is 25 times higher than the average citizen's.

Answer

All are correct.

It took me a while to figure out the role of "less" in the first sentence.  It is a "comparative adjective", like "smaller".

Answer

Your sentences are quite natural already, but here are slightly refined versions to enhance flow:
* Dark chocolate contains less added sugar than white chocolate.
* Organic oranges have 30% more vitamin C than conventionally grown ones.
* Cars today are far more fuel-efficient than those made in 1990.
* The President’s salary is 25 times higher than that of the average citizen.