CD Speed - Pressed CD
In addition to the file copy test, we also used Nero CD Speed to test the drives' ability to read a data disc. The same three discs (pressed CD, CD-R, CD-RW) from the file copy test were used in the following tests. First, the pressed CD:

Pioneer drive reading pressed disc

The Pioneer results make its 10.3X-24X rating look a little conservative. The drive starts at 11.25X and ends at 24.61X. This is even more impressive because the test disc wasn't completely full; many drives don't hit their manufacturer's "max" ratings until they're reading the 650th megabyte, so that makes this score even better.

Philips drive reading pressed disc

However, as impressive as the Pioneer's score is relative to its rating, the Philips drive sticks close to its rating as well, which puts it well above the Pioneer. While the Philips doesn't exactly hit its 32X rating, it's likely that it would with a full disc.

CD Speed - CD-R
Next up are the CD-R read tests:

Pioneer drive reading CD-R

The Pioneer takes a significant hit moving from a pressed CD to CD-R. Its starting speed drops from 11.25X to 7.48X, and by the end of the disc it's only up to 16X. This is a good example of how the speed of some drives can vary widely depending on the media being read.

Philips drive reading CD-R

The Philips, meanwhile, keeps right on going. In fact, its CD-R scores are slightly higher than the pressed CD scores. Given the Philips drive's indifference to media types in the file copy test, this is more or less expected.

CD Speed - CD-RW
Finally, the CD-RW tests:

Pioneer drive reading CD-RW

While the Pioneer's speed dropped substantially moving to CD-R, the CD-RW scores at least match the CD-R results.

Philips drive reading CD-RW

The Philips drive once again betters its previous best score. This is an unusual result. In my experience, most drives slow down quite a bit when reading rewriteable media.