been doing some digging on this lot of looking on the net there is a website if you put your reg no. it says £165.00 a year when you read the government website it says cars registered after 2017 dual fuel its £165.00 that applies to new cars not Japanese imports registered after 2017 . my tax was £280 last year now £295 that tells me they are taxing you on the size of the engine maybe i did get a discount maybe my tax would have been a lot more with out the lpg . hope to find out soon as i have emailed dvla tax office to find out will let you know the out come.