Its also the practicality though, I occasionally have to go to the petrol station twice a day. If the economy was 50% worse, then I would probably have to stop on the motorway and bend over backwards, in addition to wasting time standing at the pump.
Also, if say you got 25mpg average and did 10k miles a year, fuel costing 124p, that would be £2200, but what if you get 15 mpg, it would cost £1500 more a year. Some people don't have 1500 more to spend (or just the moral of spending almost £4k on fuel a year... Doesn't mean we should be buying more efficient cars, but I think its good info to know. I'm going to be doing over 600 miles on Mon-Wed, the majority of that being motorway but then hopefully some clear mountain roads at my destination. Not a worry and not that I can't afford it but I think its good to know.
I guess some people truely don't care though... or as you said, had a less efficient car so the S3 is great compared to it lol.