In the Iron Man movie Tony flies the Iron Man armour from Miami to Afghanistan, roughly 7800 miles.
EDIT: Just found this (funny) image, New York to Washington in under an hour?!? :)
Cinematic Iron Man has been show to have the ability to fly about 15,000 miles and engage in combat against standard non-superpowered enemies for about an hour without appreciable issues.
Given he was seen flying alongside jet aircraft, he can achieve at least Mach 2 and sustain it. Unfortunately, this would make a trip from Miami to Afghanistan take about 5 hours each way. It is possible he is even faster than Mach 2 since he outruns said fighter planes when he is using his back-mounted afterburner.
If he were to engage in a maneuver used by Earth-616 (Marvel Comic Universe) Iron Man, called the sub-orbital hop, he could achieve near orbit, allow the Earth to turn beneath him and come in at re-entry speeds making the trip in under 3 hours give or take.
We can't know if he could circumnavigate the globe, we are never given specifications sufficient to make a determination. Even though he appears to have sufficient power due to the Arc Reactor, we cannot be certain of his armor's repair tolerances after such a long sustained flight. Most modern aircraft need at least the same amount of time spent repairing them as they spent flying. More complex aircraft need even more time in maintenance per hour of flight.
Iron Man in the comics has had multiple suits of armor each with varying capabilities. His earlier suits are far less powerful than his later designs and his latest designs are only incrementally more powerful with each iteration. What they gain is greater mobility, ease of use (though probably not of design or repair) and overall durability. While each suit has increased his power significantly he is still third in overall fighting capability after Thor and the Hulk.
Writers were terribly inconsistent in their depictions of his armor's capabilities and were very remiss in addressing any armor's overall speed, acceleration and duration of flight time. Each armor enhanced Iron Man's strength speed and stamina, made him capable of flight for short distances.
Iron Man never carried fuel in his early armors, so how he was able to maintain long term flights was never explained. But the earliest designs had very limited flight times sometimes less than five minutes. While his later designs became faster, how far he could travel was improved as well. Speed varied depending on the writer.
By the late seventies, He was often seen flying alongside jumbo jets (600 mph) for brief periods but rarely traveled a distance greater than the continental US. If he traveled out of country, he would fly commercially, or with a private jet, bringing the Iron Man armor along. This implied distance may have been a limiting factor even if the armor was capable of great speed.
By the early eighties, He was consistently able to fly across the US in a hour or less. He could use his normal armor to perform sub-orbital hops, achieve high altitude and allow the earth to turn beneath him before dropping back to Earth.
Sub-orbital hops made it possible for him to cover far greater distances in much shorter times without draining his power supplies unduly. Sub-orbital hops were faster than flying directly, but for earlier armor designs came with their own inherent risks, including air supply, radiation exposure, and re-entry control issues. Sub-orbital hops were used later as the armor designs improved integrity, control and durability.
In the early eighties, Iron Man began to use specialty armors and one such armor was his Space Armor. (First Appearance: Iron Man (vol. 1) #142 (January 1981)) Even though his normal armor could function in space, it was only for very brief periods. His Space armor was one of the few armors which could achieve escape velocity moving at 25,000 miles per hour without a support package (a booster pack which would disposed of the same way the space shuttle might).
Comic Iron Man is now routinely seen as fast as fighter jets (Mach 2-Mach 3), able to chase them down, has a high degree of maneuverability and can manage to even keep up (for short bursts) with fired missiles at Mach 5. Where he vents heat, stores fuel, shunts momentum for directional changes is beyond the scope of this article...
Cinematic Iron Man has had a history similar to his comic counterpart, with one major exception. Cinematic Iron Man has always had a powerful near-nuclear energy supply so his early suits rarely had issues with running out of power like his Earth-616 counterpart.
With the inclusion of the Arc Reactor in the early genesis of the character, Earth-199999 Iron Man has enjoyed "free energy" and is thus able to fly indefinitely, unless there is a particular bit of wear and tear on the armor we are unaware of. Since we don't know what the maintenance cycle is on the armor, we are not sure how far he could travel on a single repair cycle.
The latest versions of the Iron Man armor have similar flight capabilities: as fast as fighter jets (Mach 2-Mach 3), able to chase them down, has a high degree of maneuverability and can manage to even keep up (for short bursts) with fired missiles at Mach 5.
We have not seen how far the armor can carry Iron Man but since he has been freighted around with Thor and Captain America by SHIELD perhaps we are to assume there is either a limit to top speed or a limit to distance flown. There may (in a fashion similar to airplanes) micro-stress fractures which the suit may develop over time which may ultimately reduce how long a suit can be used for, or requiring greater service times.
This might require Stark to monitor how much airtime, combat time, and how much stress a suit may be able to take before requiring repairs. He may be able to fly halfway around the world, fight a battle against a variety of enemies, but will the suit be in any condition to fly back afterwards is the question. Sufficient damage may reduce his top speed or his flight range.
In the extras from the DVD, an omitted scene had Tony Stark already on the Middle East via Stark Industries jet and holding a function/soirée, these scenes were later edited out -likely for brevity.
Your comic strip and the movies aren't compatible. In movies (and, many comic series), Ironman's armor is powered by portable fusion reactor.
If we believe Avengers movie (which is in canon with Ironman movies), he can circle the globe many times without reactor replacement (In Avengers, he used his weaponary system for many hours).
When it comes to speed, it has never been mentioned directly in the movies. But, we've seen him flying faster than a nuclear missile (Avengers movie). It means, he can travel at hypersonic missile speeds like 2.5miles/s, 5miles/s etc. He might have traveled to Afganistan faster than this because he combat against the same terrorism he just watched on LIVE TV.
I think that the best answer is that since the iron man has an ARC reactor which basically is a super power source which never runs out, well it does but after approximately 400-600 years, well beyond the human life expectancy. Now in his boots, tony stark has some sort of very powerful rocket engine which seems to last for ever, this is because the rocket is a VASIMR engine or something equivalent to it in the marvel world.
You can see how the VASIMR works on Variable Specific Impulse Magnetoplasma Rocket (Wiki)
This type of engine can use any gas as fuel and act as either a rocket or ion thruster enabling very high efficiency, simply such a highly technologically advanced suit can simply extract hydrogen from the air by pressurizing and condensing rammed air thus giving water, then through electrolysis hydrogen is used to power the equivalent VASIMR engine, and since oxygen is also produced, it can be used to supply oxygen to the suit's user, enabling the suit to fly incredibly high where the atmosphere is thin enough to cause minimal drag yet provide enough water vapor for the suit, in case the suit needs a quick refill, it can simply descend to lower altitudes where the water vapor content is high, by flying at high altitudes it is able to achieve hyper sonic speeds of mach 5 (3840mph) since drag is very low. Also it can use ambient air to mix nitrogen with oxygen to get the 78%-21% mix which humans need to breathe properly at approximately 14 psi of pressure so that the suit remains pressurized.
