I recently bought one of those car adapter chargers (it was under 2-3$ at a sale) and made a video about it here:
In the video I've replaced the 34063 with a ncp33063 (same thing, just lacks inverting mode i think) because I either shorted the original chip or it was damaged in the first place.
Since the title of the thread has 2A in it, I guess I should point out that most car adapters using mc34064 or similar chips aren't capable of actually doing 2A, and some don't have components optimized for high currents... for example mine was more "tuned" for 9-10v rather than 12-24v (it was more efficient with lower voltages, up to about 400mA)
There are cheap buck regulators that can do 2A or more without any problems, like those LM25** you can find on eBay. You just have to package them in a small box and you'll be fine. If you want to, you can replace the capacitors with some high temp ones (Panasonic FR series for example, 8-10k hours at 105c depending on capacitor size) and the buck regulator itself should handle summer heat under a car windshield just fine if you add some heatsink to it.
later edit:
Here's 2 pictures of the charger I opened up in the video .. output cap is just something I had around (the original one exploded when i powered it up, as the original damaged mc34063 passed the input voltage directly to the output)