Didn't Astro Pneumatic offer automotive specific tap and die sets. I haven't heard anything about them for a while though.
Yes, Astro once sold a great automotive metric set, but it's long gone.
Gearwrench sells a pretty decent set nowadays, or honestly in the OP's shoes I'd assemble a set of the sizes I need from scratch, using higher-quality stuff from Zoro, McMaster, Grainger, and/or MSC. Get the taps and CORRECT size drill bits; I have no idea why so many sets do not include the drill bits, or force you to use the widely available approximations marked in barleycorns that are all we can find on the shelf in the US.
For example, I have M6x1.0 taps stamped with the drill bit size 13/64". This converts to 5.16mm, but the correct drill bit size would be 5mm.
This only works when you know the thread sizes you need, of course; as noted above, Asian vehicles use finer pitches in 10mm and above. 'Merkin and Euro vehicles have different standards, so research these if that's what you're working on. Or buy everything...
And of course as many have noted, the Lang thread restorers are far more appropriate in "cleanup" situations; reserve the taps for actual tapping. For spark plug threads in cylinder heads, there are special thread chasers.
Dies are very, very rarely needed. I think I've threaded the outside of a brass tube to make an adapter a few times. I have used a die to clean up threads when I didn't have a restorer of the correct size. Unless you have a lathe, it can be ridiculously difficult to get metric rod or tubing in the US of damn A with diameters appropriate for metric threads.
Lastly, I'd also buy a thread file, as well as a few good triangular files. These are fantastic for cleaning up external threads. Cheap, effective, and not one mechanic in ten knows they exist.
A decent set of thread inserts and tooling is another nice luxury to have around, especially if you do much fiddling with vintage metric machinery.