The official announcement for the new Audi A4 is expected some time today (august 28th). In the meantime, in an announcement about "efficient drive systems", Audi has released some interesting tidbits that help us put the new A4 (B8) in perspective with the previous two generations (B6 and B7).
In the chart above (click on the image for a higher resolution version) you can see a comparison of technical data between B6, B7 and B8 for an A4 1.8T. A first thing to be noted is the very small difference in weight, with the B8 25 kg heavier than the B6 (from 1,370 to 1,395 kg).
Another interesting thing is the passage from the old 1.8T to the new 1.8 TFSI. Power output has risen from 150 to 170 ps, torque from 210 to 250 Nm (passing through the 163 ps/225 Nm for the A4 B7), while fuel consumption is down 15% from 8.3 to 7.1 liters per 100 km. CO2 emissions are down 15% too, from 199 to 169 g/km. Performance should be sensibly better, with a 0-100 km/h time that should be down from 8.9 to 8.4 seconds.