Basically, what he said...
I used to race around but that was when fuel was cheaper and my cars were faster. A lot faster......
Anyway, I remember getting VERY stressed as the roads were very congested and there was always some idiot blocking the way for no reason who obviously missed the bit about keeping left unless overtaking... And no, I NEVER had an accident. Or caused any. Believe me, in my job I see the end result of crashes all the time (and despite what traffic cops tell you, THEY don't scrape you off the road I do, and I can think of better things to do in the middle of the night..) so I'm very observant and cautious- also 25 years of motorbikes kind of sharpens the senses. Trouble is, no matter how good a driver or how observant you are, there's always some other idiot who can do something totally random and end it all. Just watch any Russian driving vid.
But commuting 200 miles a day taught me to slow down to save fuel and I discovered it was a lot less stressful, a lot cheaper and I wasn't that much later. In the real world, doing my commute at 80 in the Golf compared to now doing it at 65 in the FL takes me an extra half an hour a day. But less stress. I'd like to say I save money, but the reality is the 180bhp Golf did 57mpg at 80 over the journey, and 75mpg when I did it at 65. The FL does it in 44mpg average. If I drive at 70 or more, the FL uses a lot more fuel..
I also use Diesel Rhino additive which works out at about an extra 1p or so a litre but means I can chuck the cheapest nastiest diesel in and get the benefits and mpg of running the top fuels that cost over 10p more a litre. I used to get about 5mpg more in the Golf using the Rhino. Not sure how many more int he FL as I've always used it.