PeterE wrote:
DieselMoment wrote:
Gizmo. I am saying the tax is too much. Diesel should be cheaper than petrol, as it is in other countries
Why, given that it is a more polluting fuel with a higher calorific density? If anything, diesel should be taxed more per litre than petrol, or both should be taxed by weight.
The cost of production argument doesn't wash, either. The pre-tax price of diesel in the UK is higher than that of petrol, suggesting its production costs are, if anything, more. As we have said before, both petrol and diesel are co-products of a fractional distillation process, so their cost of production is unlikely to vary significantly, and distribution costs will be pretty much identical.
Now you're entering into a debate about the moral ethics of road fuel taxation. Also, I still do not agree with your assessment that "diesel production costs are, if anything, higher than those of petrol" - unless you're incorporating oil company profit into the "production cost".
The diesel that I put in my car at 90p/ltr is, it has to be said, not that different from heating oil. In fact I could probably put heating oil in my car and get reasonable performance. So I had a poke round to see if I could get a heating oil price. I found a .PDF document produced by the States of Jersey government. Last year (2004) the average price of heating oil was 25p/ltr. So I feel confident that the oil companies would be capable of producing genuine diesel fuel for about the same price, or not more than 30p/ltr. States of Jersey document (.PDF):
http://www.gov.je/statistics/content/pd ... gjun04.pdf If you still maintain that the tax on fuel is only 47.1p, then diesel would cost about 70p not 90p. Do your figures include VAT?
PeterE wrote:
The reason diesel vehicles are more economical is that diesel is a denser fuel (a lower fraction of the distillate) with more energy per litre. It's nothing to do with any inherent superiority of the compression-ignition process.
It might have something to do with the compression ratio. Please refer to this analysis and comparison between diesel and petrol engines:
http://www.iea.lth.se/people/evs20_karin_jonasson.pdf I have not read all of this document, but it makes clear that as well as diesel fuel having more energy per litre (as you stated correctly - the actual figure I have seen is 17%) the other factor is the diesel engine's much higher compression ratio. The document indicates that a petrol engine cannot operate at more than ~33% efficiency, while a diesel engine can operate at ~45% efficiency.