I was hoping for three numbers: the leanest is idle/low cruise, 2nd is normal acceleration, third is when the secondaries open near WOT. Granted, computer controlled EFI can produce literally any mixture, but from a carburetor perspective those 3 numbers are what carb tuners take from the charts to select a tapered metering rod and primary and secondary jet size.
In the EFI world, the 3 number system might still applies to some degree--lean at low power, stoichiometric under moderate load, and rich (to a point) on heavy load. That point is limited by 1) the engine's ability to actually burn the fuel, and 2) emissions. Excessive enrichment will kill your cat, so there's a sweet spot in WOT enrichment beyond which you hurt reliability and produce sub-optimal power. Emission numbers start to rise as soon as you move rich of 14:1, so if you're selling in fruinia, you'll need to put a reasonable cap on your WOT mixture. <--Hours of immersive game play right there.
My two cents is that an arbitrary number would cut into the immersion. I should not have come off as complaining because what you have is a great thing going--Maybe an arbitrary number selector could be used to produce fuel curves in a similar manner to the suspension presets, but for fine tuning, I'd like to be able to tweak the low, middle and high end of the fuel curve with power, efficiency, emissions and reliability consequences. the game already has the first three,
One arbitrary number would make me sad. All that said, 16:1 is where best economy is. You can't apply power at that lean setting, but a VVT engine with the magic of in-cylinder exhaust scavenging can cruise 60mph with a 16:1 mixture and a cylinder full of exhaust gas. Just a bug in your ear--I spend lots of time tweaking those engine settings. It's addictive. One number would suck the fun out.
I've got to admit this is probably the most realistic vehicle builder I've ever played. All day I deal with real-life engine numbers, test reports, and occasionally a broken prototype, then I come home and play Automation. It's that much fun. I also play Automation at work. But it looks like I'm working.
PS edit: I've been an automotive engineer for years and I could dig up some useful charts if you think you could use them. It might surprise you how efficient a 4-bbl carb can be. Gas-crunch-era vehicles in the US had owners putting some very lean-running jet/rod combinations--a lot of burned and broken engines, but a lot of good data for the 70s and 80s. 22mpg from a 4000-pound V8 cruiser with a 4-barrel carb earned bragging rights. But like most engineers, I would never release anything because I never stop tweaking