i wont be remapping it or modifying in any way, i just need a reliable daily driver, i bought a 306 hdi as a cheap car but it has cost me a absolute fortune so time to cut my losses and get a good old vauxhall. im liking the omega as its very plain and draws no attention to itself. yet its fully loaded and bargain priced. i thought they were quite rare but 4000 members tells me otherwise.
In all honesty if you want an Omega, you won't be toooo worried about fuel costs.
Therefore, get a V6. Preferably a 3.0, or failing that a 2.5.
My 3.0 V6 facelift Estate Elite does at least 32mpg on a combined run, the fuel is around 13p cheaper than diesel and is that much smoother. It's also much more DIY friendly (Eg, easily changable cambelt) compared to a TD, by which time when the timing chain has stretched, you have a major job on your hands.
Say knocking around you average 26mpg in a V6, at the moment petrol is 97.9ppl, so £4.44 / gallon. That's only 17 pence per mile.
So for the cost of a pint, you can travel 18 miles - or 17p per mile.
Unless you are doing tens of thousands of miles per year, or running a business travelling up and down the country

- you don't need an "economical" omega

You could of course, get a 3.0 / 3.2 and LPG it - although the gap really is closing between LPG and petrol
