S. 172 RTA 1988 is the only exception to the privilege against self incrimination in Western Europe. You either name the driver, which in your case would constitute a partial confession (admissible as evidence that you were the driver), or you get 6 points and a Band B fine (capped at £1000, plus 40% surcharge, plus prosecution costs).
Without a confession to being the driver, the prosecution would need to prove who was driving some other way. For routine speeding cases, they wouldn't even consider attempting to do that. For dangerous driving, they are more likely to try to obtain some evidence, but it is far from certain that they would be able to prove that you were driving on that occasion.
N.B. we cannot advise you to break the law, but we can tell you what the consequences of doing so are likely to be.
