I would say reg fee each of them but you never know. I would price them very competitively to start out with - XX-2XX range to see how it goes. If no bites - then lower price then drop after year 1 if no sale.
Echoing what someone said - see what is selling before you buy another domain. Seems you are new to this from the quality or lack thereof, of the registrations. Check this section -
https://www.namepros.com/threads/report-completed-domain-name-sales-here.83628/page-990#posts, and sites such as namebio.com, dnjournal.com, etc. Also subscribe to reputable domaining blogs - see what people are buying and what is selling.
Think products with big markets and lots of consumer activity. One way to judge comsumer activity is to see if there are lots of ads in Google for that market.
I am not in the loop but I would think with the push towards green energy like solar and electric worldwide - I would not have regged that diesel domain. It may sell but I am thinking the world is moving towards green energy.
Besides, that diesel domain seems very niche to me. I would think diesel and gas are sold together - as in - at the same place - typically - so a company would prefer a domain that brands them in that collective manner. I could be wrong on this but that would be my thinking.
After coming up with big markets in demand, like crypto, flowers, security, health, games, think of adjectives like best, top, epic, bright, etc, and see if they can be paied with those big markets. E.g. - like top crypto dotcom or best energy dotcom, or epic market dotcom, etc. These are taken but hopefully you get my drift. There are some good adjectives + markets available if you look long and hard enough.
Make sure the adjectives and the markets go together. Like easy benefits makes sense whereas as ease (noun/verb) benefits does not at all. Even if you reg noun + noun dotcom or verb + noun dotcom - make sure the combos make sense and appeals to that wider market I spoke about.
Even if you register Geo domains, like LA +market or NewYork+market - make sure the market is vibrant.
Speaking of Geo domains, some people have success regging and outbounding these names. It is doable - but it is a massive grind, you will need tools to help you, you will need to price very competitively on average, and be prepared to spend a bit to have a big enough portfolio to really have a go. Check this forum for how people have done it. Personally - I have never had success with Geos but perhaps I never went at it hard enough.
There are many decent names available even as hand registrations if you dig deep. Do not be afraid to pass on one registration if it falls short. Keep digging until you find something reasonable at least.
For now, stick to dotcoms and shy away from brandables, hyphenated domains, IDNs, numercals, etc, three-worded domains, until you learn a bit more. Keep regs short. I personally typically max out at 16 letters but I aim for less.
If you have the capital, you can quickly up the quality of your registrations by getting involve in auctions at places such as Dropcatch, Godaddy, NameJet, etc. If you are low on capital - Godaddy Closeouts, expired domain databases that are free (expireddomains.net), lower priced auctions at Dynadot and Sav, and Bargain Bin domain section here at Namepros are good places to check.
Good luck and do not be anxious just to register something. Dig deep - look for quality.