Hi,
We created a post in the same niche https://www.basecampers.com/vw-t5-vs-vw-t6/ It ranks top fold, sometimes position 0 for 'vw t5 vs vw t6' in the UK
In this article, we didn't concentrate on keyword density or bolding keywords, but rather make really informative valuable content. We did look at surrounding queries and make sure we answered those too.
Google bold the search words in the SERPs, so they know they are there. We have had many successful blogs receiving 10's of 1000's of views per month without that technique. Although we would emphasize a word with a tag IF it was important and was bold to aid the user by reinforcing something we want to get across. Then it would be of value.
Does that help? 