In short, no!
To get there in half an hour, you
doubled the speed - which halved the time taken at the original speed.
Doubling your speed again has the same effect; i.e. you take half as
long as you did at the previous speed. So you'd get there in fifteen
minutes.
If you doubled the speed yet again, you'd get there in
half as much time again (7 minutes 30 seconds) and so on and so forth.
If you think about it, in order to get there instantly, you'd have to
have travelled in an infinitely short amount of time (since travelling in no time means not travelling at all), which means you must have travelled infinitely fast - which for many reasons is quite impossible.
In
future, to calculate the time taken to reach your destination, simply
divide the distance you need to travel by the speed at which you intend
to travel - provided that you use the same units (km and kph, or miles
and mph - no mixing and matching!). 200km at 50kph is 200 divided by 50,
which is 4 - so you'll get there in four hours.
One more thing - although doubling your speed halves the journey time, this only applies up to a limit. Nothing can travel faster than the speed of light in a vacuum, which is around 300,000 km per second. And anything larger than the tiniest subatomic particles can't get anywhere near that speed anyway, due to strange effects that, generally speaking, are best left to physicists =)
