Fuel taxes vary from state to state. The fed is the same across the country but the states can do their own thing. It is not based on a percentage but a flat rate per gallon.
For the fed diesel is 24 cents per gallon, for gasoline it is 18 cents per gallon.
The states are all over the board most of them are in the 20-30 cents per gallon but some lower some higher
for diesel Alaska has the lowest at just under 9 cents per gallon and Pennsylvania the highest at 74 cents per gallon followed by Washington at 49 cents
For gasoline Alaska has the lowest at the same just under 9 cents per gallon and again Pennsylvania the highest at 57.6 cents per gallon followed by California at 51 cents per gallon.
https://igentax.com/gas-tax-state/
While I have nothing against ev vehicles they currently wont work for me perhaps in the future, nor do I feel they are some sort of climate/pollution/anything panacea, nor do I care for the myriad of subsidies direct or indirect that they receive. It does somewhat irritate me and it certainly gets worse the longer it goes without being dealt with is they do not currently pay any type of road tax as has be previously mentioned in this thread. Weight is weight and does the same amount of wear and tear on the road as any other vehicle on the road regardless of the type of engine it is using.
As far as using dyed fuel in farm vehicles can get a little grey, while certainly usable on the farm once out on the roadways is where it can get a bit grey as federal law says any vehicle on the roadways cant use it except in declared emergencies, or severe fuel shortages. Farmers and ranchers can get a fuel tax rebate for their on farm use. Also at least in Colorado farm plates are only valid within 150 miles of your farm/ranch.