Re: What fuel do you use?
It is to laugh. Sometimes I know just how to perturb people.
For them that may care, the whole octane thing stems from salesmen waving their ties over detonating engines. (I'll leave what that means to the students with one hint: Thomas Midgley )
More is better right ? Not really, higher octane requires more refining and you get less from a barrel of crude. Oil that is.
Gasoline has the same energy (btu/pound) regaredless of octane. What higher does is burn slower and combusts at a higher temperature. So a higher octane needs more advance to peak chamber pressure at the sweet spot (depends on the engine but generally between 5 and 15 degrees ATDC).
Back in the day, when we put premium in an engine designed for regular we needed to bump the timing a few degrees to compensate (like when you drop a QJ & headers on a 283 and back the lifters off a tad).
So a computer car designed for premium gas may not be able to retard the timing enough for regular gas and may burn too soon to hit the sweet spot. Best case you lose a little power, worst you get detonation and the engine, not having any other way to cotrol it like VVT, tosses in A Lot of retard which loses power and may cause overheating. Like I said, it really depends on what the car can do when trying to run on trash gas. Of course with OBD-II you can monitor the actual timing advance and injector pulse width.
Now I do not "hate" any engine, transmission, axle, or car. I even had several Vegas and an Astre (do draw the line at a Daimler SP250). The MB is a fine example of the last century just like my Judge has an engine that was pushed past any design limits because Pontiac never could afford a Big Block. And I would really like a five speed. OTOH it can turn 29" tires
Or take my 80's Reattae with an iron block pushrod "odd-filre" V6 (something it shares with the MB and a result of building a V6 that can go down the same line as a V8 (cost issues). All done at 4800 rpm but can cruise all day at 2000 rpm at 70. On 87 PON.
In the opposite corner is the Pentastar in my Jeep. DOHC 4valve, VVT i&e. Pretty Much SOA in 2011 and very similar in design to the current MB 3.5 liter
Also back in the day, there was an SLK200 with 134hp I4 that needed a really low first gear and why build more than one manual trans when most buyers of the 3.2 will get automagics anyway. Bean counters rule.
I really like my XF, it is really nice now that I fit for those long trans-Florida trips or when the weather is not right for my 'vert.
Would like it to "be all it could be" but not enough to change what it is (beyond what a sawzall can do). Otherwise I would not be here (with my goad 8*).