Well, each ship will have their own 'maximum warp'. For the Kelvin universe, we were told that the Vengeance was 3 times faster than the Enterprise (sporting more advanced weapons, etc.). As for the Scimitar vs the Ent-E... nothing was stated on screen on which was faster... we just saw the Scimitar was able to catch up to the Ent-E while cloaked and fire at it while at Warp... but from the initial tactical description, the vessel was supposed to be 'better' in every respect than the Enterprise-E (or at least I think that was the intent). The actual Warp speeds of Ent-E and the Scimitar were never stated on-screen, so those numbers wouldn't be valid. In fact, on-screen, no SF ship was able to fly faster than Warp 9.9 apart from some anomalous situations (or an external force) that pushed the ship to excessive speeds by accident. The USS Prometheus (as seen in VOY Season 4), was the first SF ship capable of achieveing and maintaining Warp 9.9 without issues (as was confirmed by dialogue) under its own power. In fact, even Voyager was stated on-screen (in dialogue) that it can sustain Warp 9.75 for 12 hours (not 9.975) - whereas at Warp 9.9 (maximum warp velocity), it was starting to shake itself apart. Previous on-screen dialogue from both TNG and Ds9 confirms that SF was at around Warp 9.5 - 9.6 as a maximum which can be sustained safely for most ships - even older classess which were upgraded (except for newer ship classess like the Galaxy class that were able to push to 9.8 'at an extreme risk' for a limited time).
Ah, missed that 'examples' bit... still I do think my post stands if we go by what was stated on-screen.
STADI: Intrepid class. Sustainable cruise velocity of warp factor nine point nine seven five. Fifteen decks. Crew complement of one hundred and forty one. Bio-neural circuitry.
And yet in the episode The Swarm, this was said: JANEWAY: All right, let's get through this as fast as we can. Mister Paris, what's your recommendation? PARIS: I'll try holding warp nine point seven five for as long as I can. Also, episode Threshold: KIM: They're approaching warp nine point nine. CHAKOTAY: Increase speed to match. COMPUTER: Warning. Nearing maximum warp velocity. Structural collapse is imminent. CHAKOTAY: Are we in tractor range? KIM: No, and they're still accelerating. Warp nine point nine seven. COMPUTER: Warning. At present speed, structural failure in forty five seconds. CHAKOTAY: Reduce sped to warp nine point five. Keep a sensor lock on them as long as you can. This dialogue is more in line with the premise that VOY could never achieve 9.975, and this is canonically correct if you go by speeds we heard in TNG and DS9 (which were all below Warp 9.6 for the most part) under the ship's own power. Fruther supported by the next piece of dialogue from 'Message in a bottle': EMH: I've accessed the navigational logs. We're at warp nine point nine, heading straight for Romulan space. EMH2: This vessel was designed to go faster than anything in the fleet, so we'll never be rescued. Warp 9.9 seems to be the new maximum stable cruise velocity starting with USS Prometheus which achieved and sustained it without structural issues (Voyager on the other hand seems to have been limited to Warp 9.9 as the 'absolute maximum' which it couldn't even sustain for 1 minute... making 9.75 a (as stated in The Swarm) a speed which could be sustained for about 12 hrs. 9.975 seems like an error... and doesn't make much sense unless SF made a massive leap in power generation and Warp drive speeds... which would be nice if it happened (because Warp 9.975 would have returned ship back to earth in under a week across 75 000 Ly's), but no.
There's also this line from Relativity JANEWAY: Seven hundred thousand metric tons, fifteen decks, and computer systems augmented with bio-neural circuitry, top cruising speed warp nine point nine seven five. By the Time "The 37s" came out, Paris told Earheart max speed was PARIS: Warp nine point nine. In your terms, that's about four billion miles a second. Perhaps it was Paris making the verbal slip in The Swarm, rather than Janeway and Stadi, or perhaps given that Voyager was stuck on the other side of the galaxy without access to a Starbase or repairs, it's quite possible its maximum warp speed was lower than it was when it launched (and got lower as the journey progressed) I'm not sure EMH2 would have access to classified information about maximum velocity of ships.
Yes, but its' also interesting that speeds in excess of Warp 9.9 never actually materialize across TNG or Ds9 under the Starfleet ship's own power (except in rare circumstances where an external force or an alien pushed the ship to an even bigger extreme) and were in fact limited to about Warp 9.6 as a maximum. Similarly, across Voyager as a series, Warp 9.975 is only MENTIONED a handful of times... but actual speeds the ship was able to reach never went beyond Warp 9.75 (or 9.9 for that matter). In fact, the ship was regularly cruising at Warp 6.5, and even 'made up the lost time' at the end of 'Basics part 2' by using Warp 8. While, Warp 8 is certainly faster than Warp 6.5, it really makes no sense to go that slow if the ships 'maximum sustainable cruise velocity' was supposed to be 9.975. Paris was VOY's pilot. Its his job to know what the ship can sustain safely in a given amount of time. Or, the writers made a stupid mistake which was a product of not looking into previous series of TNG and DS9 to understand that all SF ships were limited to Warp 9.5 or 9.6 for the most part (if their engines even allowed them to reach those speeds in the first place). The Enterprise - D had a maximum sustainable Warp factor of about 9.6... in DS9, a Nebula class ship (incidentally also called the Prometheus - but obviously wasn't the same as the experimental 5 nacelle ship seen in VOY season 4) was modified by O'brien to be able to sustain Warp 9.5 'in a pinch'. The Defiant couldn't even go past Warp 9 without shaking itself apart (not unless you shuffled enough power into SIF - which required syphoning power from weapons). TNG and Ds9 clearly established some fleet limits of Warp speeds in the 24th century, and while we know older ships can be upgraded and modified to be just as fast and efficient as new ones, its a process that takes a bit of time tinkering with its systems (but its still worthwhile). Sure, it would be nice if Warp 9.975 was Voyager's actual maximum cruising speed, but past Warp 9.9, speed and power consumption increase exponentially with every increment... meaning that 9.975 would have allowed VOY to cross 75 000 LY's in less than a week, and it would had to have either a far more powerful Warp core than the Ent-D or far more efficient Warp engines by orders of magnitude... and while I'm open to the idea that a Warp core on the Intrepid might be equally or slightly more powerful and the engines themselves far more efficient, I also doubt nothing would be said on-screen about it having such capabilties. Warp 9.975 was also described as 'sustainable cruise velocity' by Stadi, meaning VOY SHOULD have been able to sustain that speed indefinitely without experiencing structural problems (or it being a limitation in sustaining the speed in question) - and it was NEVER able to do so since Warp 9.75 was already a speed the ship struggled to maintain. The writers could have simply thrown Voyager about 206 million Ly's away and say that at Warp 9.97 it would have taken the ship 75 years to get back. THAT would have been far more impressive and would have also told us SF made a massive breakthrough in Warp speeds and efficiency with the Intrepid class ships - which if you ask me would be far more in line with UFP which is comprised of over 150 different species where technology and science evolve exponentially (and would suggest this technology was in the works building on what Enterprise-D experienced with the traveller, and other attempts) - but alas, no... this didn't happen. I also hypothesized that one of the issues VOY's speed was impacted due to the initial damage the ship sustained in its transition to the DQ... but this would have 'eventually' been repaired (maybe not in the first couple of seasons due to continuous problems with the Kazon attacks etc. - but by third or fourth, yes)... so, I can see it being an issue initially, but not ALL the time - after all, UFP ships have enough technology to make all repairs they need to in the field very fast - and have the ability to replicate matter out of energy itself... or just use regular matter to convert it from one form into another - VOY could have simply gone to an uninhabited star system, hooked itself up to a star for power, or scour asteroids etc. for regular matter which it could convert from that form into what they needed. A starbase or a drydock simply has dedicated facilities that make the work go faster. Heck, even the NX-01 crew in the mid 22nd century was able to install Phase Canons in 2 days while in the field, compared to initial statement which said the work could only be done by a dedicated Earth facilty in 2 weeks. The EMH1 was able to read what the USS Prometheus (5 nacelle ship) current velocity was (Warp 9.9), and EMH2 merely said the Prometheus was designed to be fastest in the fleet (after EMH1 stated they're at Warp 9.9). This was the first time a Starfleet ship was seen to travel at Warp 9.9 without experiencing difficulties of any kind. Who knows, SF may have given EMH2 higher privileges than EMH1 (which was initially conceived as a supplement only) on the Prometheus itself given how only 10 people in SF could operate it (which probably isn't accurate since the Romulans easily could), and the fact the EMH2 was integrated as part of its systems. If the USS Prometheus was capable of going faster than Warp 9.9, then don't you think the Romulans would have done that? Given that we saw previously Voy's hull threatening to collapse when at Warp 9.9 for under 1 minute... and previous dialogue Paris stating he could try holding 9.75 for as long as he can (and his subsequent statement to Amelia Earheart about how fast VOY was [Warp 9.9 which translates to 4 billlion miles per second]... I think 9.975 was an error made by the writers and was supposed to say Warp 9.75.