Hi please can you help me?

I'm aware with an old car like this, my mpg will be significantly lower, however on recent calculations, it looks like I'm getting around 16mpg.

I'm weighing up buying a new car for a few reasons, one of them being as my fuel costs are around £200 a month.

My logic is that if I get a car that has 30mpg or more would roughly double my fuel economy. Is this right?

Example - I've seen a 3series BMW 2005 plate that honestjohn says would get 31-68mpg. Based on these figures, I'm thinking at worst I should at least double my fuel economy, so it would be £100 per month instead of £200.

Have I got this right?

I was spending a 120 a week on fuel on my 1.6 petrol getting about 30mpg swapped to a 1.8 tdci with 50mpg it's now cut my bill to £100 per week so nearly doubling the mpg does not always half the price just something to consider

16mpg is too low for a 2ltr petrol unless it spends all it's time in town, it sounds like the car could do with a good service, I had a 2ltr 1999 Mondeo with 80k on the clock and regularly got 42mpg. If you change to a diesel you need to do more than 12k per year to make any savings over petrol.

http://www.fordownersclub.com/news/diesel-drivers-burning-money/

Thanks for your replies guys, I'll have it looked at. Cheers