Fuel Prices - can we afford cars in the UK any more?

Fuel prices in the UK are at the highest ever.  The Government is under huge pressure to reduce the duty on fuel by even 1p per litre and the cost per litre continues to climb ever nearer £1.50 per litre for diesel (in my case).  With a whopping £250 per month going on fuel for myself alone - never mind OH we are in fuel poverty from Diesel, not counting other amenities.
So what can I do to reduce this bill.
Obvious but cut unnecessary journeys.  A round trip to the supermarket for something I have forgotten is a staggering 24 miles.  Or if I think of it in terms of fuel up in smoke £4.80 (assuming 20p per mile to make the calculations easier!).  There is also the saving that you make from not buying the extra things that the supermarkets tempt you to buy when you pop in for "just a loaf"; my pop to the shops trips usually cost about £15 a time.....
Cleaning unnecessary stuff out of the car.  Less weight less fuel used.
One of the tips often touted is to never fill up the fuel tank (again less weight less fuel).  This is one I won't be using as modern diesels have an additive that gets squirted into the fuel to make it burn cleaner every time you open the filler cap.  It is calibrated to assume that a full tank goes in each time and at about £50 per litre for 4-5 litres is expensive to have to refill; not to mention that the particle filter or the cat will get knackered too and could land me with a garage bill for 1000's.
Driving style.  "Driving like a saint" can cut the cost per litre dramatically.  Basically only press the accelerator when you really have to (hills are wonderful things providing you are going down them!) and think ahead, if the car can slow under engine breaking without you pressing the break pedal that is more effective too.
In the wake of such high petrol prices some supermarkets are offering a few pence off per litre when you spend over the threshold amount.  One that was most recent was Morrisons where a huge 15p litre was in return for a £60 spend, hopefully this time limited offer is one they will repeat.  In my case this equates to about £10.50 if the tank is nearly empty and is well worth having providing that I needed to send the £60 in the first place.  This is the voucher that I am off to cash in today and will be the first savings to go into my new account.  Over the course of the month I intend to write down other fuel costs and anything saved on the £250 monthly budget will go into the savings earned.

savings to date=£0