The reason is many pre-97' car cd players were not designed for reading cd-rs and newer players have an upgraded chip that is designed for reading cd-r, cdrw's etc. Even if the player is cheezy cheap but new it will play cd-rs super quick. I've got a CDA-7949 which was alpine's flagship model and holy grail of HU's back in its day but is super picky on playing CDRs. CDRW's forgetaboutit just spits them back. The newer players sometimes when you pop in a data cdr it will start to play it like an audio with the seconds timer climbing. Well with my player I've tryed many things, software programs and burning methods like wav to cd audio, gap lengths etc but the biggest key on making pre-chip players read is brand of CD-R's. The BEST CD-r that works in my picky HU and my first generation TEAC home CD player is MITSUI GOLDS these badboys aren't sold in stores anymore because they were kind of overkill to buy a single CDR for over 3bucks when you can buy a spindle of cheesies for a tad more. Then next up is MAXELL "gold branded cdr's" these are the ones ONLY sold in Green 10pack w/slim cases. The packaging is the same in the 50+Maxells but they are not the same. Branded CDRs recording layer is applied differently. Gold may be Gold but the branding process is key. Then third up is Memorex Black CDR's they have branded gold surface of the older memorex golds but they just added that black bottom. I know its a headache when someone steps in your car with a cdr saying "Man you gotta hear this, its the ISH" and then they look at you like ok when is it gonna read. This is getting long, try those 3 brands peace.