A lot of variables here: What car, drive train, style of driving, what LeMans track, what aids you use, etc. Please clarify and im sure someone will help you.
True, different variables will affect the difference you now feel.
Generally, tyres seem to be lasting approximately 75% longer, although in some incidences i.e. powerful FWD cars in long races, the extra tyre life maybe a little shorter.
There's many factors to consider, so it's difficult to be precise.
Driving style, setup and power / grip ratio all play a part, even what track too, as some have naturally less wear than others.
In a recent DTM race of ours, the winner got 25 laps out of his hard tyres on a CLK with mid turbo (Grand Valley full). But he was loosing time like crazy in 2nd half of race compared to those who pitted. He had 40 sec lead after pit stop, reduced to 12 at end of race.
We did a GT1 race at Madrid, most cars around 630pp but equalized performance - medium tyres with 600bhp going through them could be made to last well over 10 laps easily, no problem.
It's definately subjective to your own variables and regulations though, looking at the replays, guys who pushed hard were burning their tyres up faster than those pacing themselves with setups for tyre wear rather than outright laptime.
It'd need a fairly comprehensive test to get accurate infomation, but generally, yes, tyres have alot more life in them than before.
If I had to take a very rough estimate, I'd say approx;
Powerful FWD (soft-ish tyres) - around 50% extra
Other(s) - around 75% extra
Other problem to consider is what PD have done with ride height in 2.08 update (and subsequently how this is affecting setups, including tyre wear). This is a whole new can of worms opened up, making accurate predictions on tyre life alot harder.
