I'd like to put forth a concept: Every 5 years, the trap speed that defines something fast (but affordable by mere mortals) moves up 5mph every 5 years. I would also argue that you could look at more mundane transportation and find a similar trend, which may also be interesting. I think this concept is interesting enough to appear in an auto rag (and maybe it has). Examples:
1980: 85mph. A 1980 Corvette ran a 15.9 @ 88 with the standard L48. There was an optional L84 in automatic only that had another 40hp, so it probably would have broken into the 90s, surprisingly to me. (http://www.caranddriver.com/reviews/198 ... est-review).
So I'll say, rough numbers, that 85mph or above in 1980 was considered pretty quick.
1985: 90mph. In 1986, the fastest Mustang LX (w/ 302) trapped 95mph and the L98 Camaro automatic the same. So I'd say 90mph is a fair line of what's considered quick. (http://www.caranddriver.com/comparisons ... rison-test)
1990: 95mph. In 1991, a 300ZX trapped 96mph. The years between 1985 and 1990 also saw the release of the Buick GN which trapped around 95. So by 1990, I'd say 95mph was a reasonable bogey for "quick." (http://www.caranddriver.com/comparisons ... rison-test)
1995: 100mph. This one is pretty easy. A 4th gen LT1 F-body would trap around 100mph with a manual trans. Affordable. There was faster stuff, but I'd argue that because of the LT1 F-body, 95mph was no longer the benchmark.
2000: 105mph. I'd argue an LS1 F-body moved the bar again in 1998, and for round numbers sake, we'll say 105 in 2000 is quick. A 2000 BMW M5 trapped about 108 but cost a pretty penny, so between that and an LS1 F-body, we'll call it 105. Furthermore, a 2001 Z06 was good for around 113 and that was considered relatively affordable, so 105 is reasonable from that perspective. (http://www.caranddriver.com/comparisons ... rison-test).
2005: 110mph. By 2005, a modest (~$45k give or take options) Z51 C6 with LS2 was able to trap 113, which I could argue moved the bar up a bit. (http://www.caranddriver.com/reviews/200 ... -road-test)
2010: 115mph. By 2010, you could argue things have leveled off a little. Certainly a C6 Z06 blew this out of the water with 125mph way back in 2006, so maybe by 2010, we could randomly peg 115 is a reasonable target for quick.
2015: 120mph. I don't know about affordability by mere mortals on this one. But, on the other hand, there is plenty of stuff that will trap around 120mph these days. It's not 100th percentile performance, which I guess was the spirit of this comparison.