While the Omega is not a good contender for this at all, I have a Peugoeot 406 TD with a Bosch diesel pump and indirect injection, which is very well suited to burning vegetable oil.
Now you CAN chuck SVO/ or (filtered) WVO in the tank and run without any mods at all, (I have done in other pugs, for huge distances) but it's not ideal in the colder weather.
What I need to do is fit a heating device in the fuel line, which contains a glow plug, to heat the oil to 90deg before it hits the injection pump when the engine is cold. this reduces the viscosity and allows it to burn just like diesel.
An additional heat exchanger is required to take heat from the coolant, to continually heat the oil before it enters the pump. This is plumbed in pretty much the same as an LPG evaporator coolant wise.
Been researching - and I can buy WVO (waste veg oil) online in 100l containers, pre-filtered for 30ppl. At 48mpg, that is 2.8 pence per mile. 100 miles on less than £3.
The conversion would cost me £100 in bits, and I'm away. Insurance are happy as long as they have a mechanics report to say it's "safe".
Thoughts?

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In case anyone raises concerns about fuel duty and tax, regarding legal implications and paying tax, I have found the below:
Following a review in late 2006,HM Revenue & Customs has announced changes regarding the administration and collection of excise duty of biofuels and other fuel substitutes (Veg Oil). The changes came into effect on June 30, 2007.
There is no longer a requirement to register to pay duty on vegetable oil used as road fuel for those who "produce" or use less than 2,500 litres per year. For those producing over this threshold the biodiesel rate now applies.
http://www.hmrc.gov.uk/briefs/excise-duty/brief1108.htm