How to say "Fastest by a large margin"?


Let's say there is a 1km race, and here is the ranking:

A: 170 seconds  
B: 301 seconds  
C: 308 seconds  
D: 312 seconds

We can say that A is **fastest by a wide margin** , because he was **much**
faster than **all** other runners.

How to say **fastest by a large margin** in Japanese?

Adapting from [ALC](http://eow.alc.co.jp/search?q=by%20a%20large%20margin), I
wrote `大幅に一番速い`, but a Japanese colleague taught me that `大幅` and `一番` can not
be used at the same time. She advised me to use only one or the other, but I
feel that the idea I want to convey (much faster than all others) is lost.




If you think about it 大幅に一番～ doesn't really make sense since 大幅 refers to a
large span and 一番速い refers to the singular fastest. As such we need an
expression that emphasizes the difference.

Looking at alc for some similar phrases, I found some stuff that might work.
Checking ["by a long
shot"](http://eow.alc.co.jp/search?q=by%20a%20long%20shot) gives us the
following:

> 大きく差をつけて、断然  
>  ・This one is better by a long shot. : こちらの品の方がはるかに良いです。

This seems appropriate to me for your situation. 大きく差をつけて makes perfect sense
since we refer to an outstanding thing by saying 差がつく. 断然 also works with a
meaning like "firmly" in terms of an extent or certainty. The example sentence
uses はるかに, which you can also translate as being something like "a distant
first."

