do burnt CD copys sound as good as originals?

The practical answer is that I doubt you'll be able to hear any difference that might pertain while listening in the car (unless you or your friends use lossy compression of the data to produce MP3 disks, or if the original source wasn't a CD but a compressed facsimile).

As far as the answer in theory goes, I've owned and tried a few different component CD-R recorders and blank media, and have found that audible differences certainly do occur. I don't burn copies on a laptop myself, but all the computer-burned copies I have been given by friends which I've later acquired an original CD of have sounded markedly inferior, but I can't say why since I don't know the details of how they were made. I do know that I've never made a copy myself which I felt sounded "better" than an original CD, but a good copy falls below the threshold of reliable distinguishability IMO.

[BTW, about another question raised above, I am sure that no dual-disk CD-R recorders convert to analog and back when dubbing, but the one dual-disk machine I tried -- a "pro" unit like the others I've had -- showed inferior copy fidelity at 1X speed than my single-well machines fed from my outboard transport, and worsened at faster copy speeds.]

I have to say, in response to Grateful, that the differences I've heard among different blank media (including Mitsui gold) have been a whole heck of a lot smaller than the "100% improvement" variety...

As it happens a Marantz Pro (model 510 I believe?) was the dual-well machine I referred to in my post of 1/7. Not that it made 'bad' copies by any means, just not as good (digital or analog) as the HHB unit I ultimately bought at the time (meaning less like the original). Differences do exist though sometimes subtle.

Sounds somewhat like the approach taken by the newer Meridian players just being discussed on another thread.