Traveling from Mainz (Germany) to Strasbourg (France) by car

When you say "better," what do you mean? Better could mean faster to someone or it could mean more scenic. The German route is the fastest, although not by much.

If you want scenery, you could ask AI (although you might get some good answers here as well). Go to Google and ask this question: "What is the most scenic route by car between Mainz, Germany and Strasbourg, France?"

The answer I got was to start in Germany but then continue over to France and drive along the Alsace wine route, which takes you "... past rolling vineyards, medieval castles, and half-timbered villages."

Of course, you could stick entirely with Germany and head south through the Black Forest, which can be gorgeous. You can take the A5 down to Baden-Baden, but then get off on the B500 route, which heads through some lovely scenery.

Thanks for the reply, Mardee! I guess I could use the AI, but I was hoping for some 'HI' (like yours)! Your idea was great food for thought. Thank you again.

When we did this type of drive, we did what mardee was saying - we stayed mainly in Germany: The Black Forest ride was amazing! South through the Black Forest, then A5/A36 to Baden-Baden (which has one of the best bath houses/spa's ever), cross over into France to A6 straight to Lyon.

A5 is very, very busy: I would stay west of the Rhine and use A63, 61 and 65, exiting at Kandel-Süd to reach the French border. There are no tolls on the French A35.
You would have to go quite far out of your way to make this trip scenic. But if you have time for stops, both Worms and Speyer are worth considering. If you go to Speyer, just follow route B9 towards the French border afterwards.

it isn't clear to me if this is a one day A-B trip or if you have some days to complete the journey.

It also isn't clear to me if this is your car, or a rental - and if a rental is it a French one or a German one?

If you only have the one day, you won't have a lot of time to stop and smell the roses.

Much as I dislike - no, hate - the A5, sometimes it is the quickest choice. As always, the A5 between Frankfurt and Freiburg im Breisgau epitomizes the worst of German autobahns. There is construction EVERYwhere. Exceedingly high traffic volumes. Shed loads of trucks, not always with the best lane control, and there are long stretches of national speed limit punctuated by plenty of 130 or 110 kph, and the usual very fast left lane runners keeping mere mortals stuck behind slow traffic. The A5 sees its fair share of Stau and accidents too. Remember in Stau which side of the lane to move to.

The A5 has a twin, the A67, a few km away from the A5 between Mannheim and Frankfurt - I usually take whichever Waze says is faster at the moment. From Mainz you might use the A60 to the A67 to Darmstadt and whichever is faster from there. Or the A63 to A61 and do an end run around Mannheim.

On the French side I find the northern reaches of the A35 autoroute between Strasbourg and Karlsruhe exceedingly boring and much slower than I imagine it should be.

Speaking of Strasbourg - do you have a Crit'Air window sticker on your car? If it is your own, you may have, if it is a French rental it will have. If it is a German rental it almost certainly won't have one. If you drive in the greater Strasbourg area you need one, and an IDP to drive in France (in Germany too but less is mentioned here about that) unless you have an EU (+UK) driving licence or an approved (read expensive) translation.

If you have more than the one day you can consider the lovely little town of Gengenbach if you are on the German side and the northern Black Forest or Kinzig Valley areas. Very close to Offenburg, which is very close to Strasbourg.

I am frequently in that area between Frankfurt and Switzerland, both sides of the border. Most recently last week for a week and previous to that last month for a week then too.

I drive my own car from England and have both the Crit'Air on the windscreen and next to it the German Umweltplakette, and I keep a digital Swiss Vignette.