I used my Freelander 1.8 during the winter averaging 1000 miles a month and obtained 31 mpg (which is good for a 1.8) This week I have been using the TD4 to see what the difference in fuel consumption is and I got 36 mpg. I know it corresponds to what most people get on here but I thought I would get a bit more

For info, my 1.8 petrol is a 1998 model with around 118k on the clock but fitted with a new (Ivor Searle re-manufactured engine) at 70k

My TD4 is a 2005 model with 60k on the clock.

Both have been tested to ensure the VCU is not siezed and they are fine.

Using todays fuel prices of £1.39 for petrol and £1.46 for diesel I worked out that for my 1000 miles per month, it costs £204 in petrol or £184 for diesel. Then factor in the road tax - £220 for the petrol, £270 for the diesel there is not so much of a convincing argument to buy a diesel, considering the much higher asking price. I know there are other factors such as more reliability from the diesel although I cannot fault my 1.8 in this regard and more performance from the diesel version.

Also noticed that the PG1 gearbox in the 1.8 has a slightly smoother gear change than that of the TD4's Getrag box but I am nit picking now

I have a 2001 1.8 petrol with 80k miles behind it, my average around Sheffield is 26mpg take it out of town and 30mpg is very easy to get.
Like you said does the minimal difference make it economically viable when you compare the fuel costs, ok the td4 has more power but I tow a caravan with the 1.8 and whilst I cannot race away from junctions it soon gets up to speed and easily maintains it with no adverse comments from other drivers. So with all that said I will be keeping the petrol engine for a few mor years.