They do, that's why we ride bikes. We can do what we like AND get away with it.

Of course, no car driver has ever exceeded the speed limit, or performed an undertaking move.

Unlike cyclists, bikers do generally ride on the road not the pavement and respect traffic lights.

Do different cars have different speed limits?

Yes. Most are limited by the power of their engine(s);some, especially German ones, are limited to 155mph by their management systems.

It seems bikes have a different speed limit and it is perfectly legal for them to speed and undertake you?

I thought filtering was legal, but I can't find any reference to it in the highway code, other than stationary traffic.

Highway Code para 163 (part)

* only overtake on the left if the vehicle in front is signalling to turn right, and there is room to do so

* stay in your lane if traffic is moving slowly in queues. If the queue on your right is moving more slowly than you are, you may pass on the left

NB "slow moving" isn't defined

It seems bikes have a different speed limit and it is perfectly legal for them to speed and undertake you?

I thought filtering was legal, but I can't find any reference to it in the highway code, other than stationary traffic.

I filtered through some slow traffic in my bike test. The examiner was not only content with it, he praised me "that's a key part of the advantage of riding a bike in the city"

I was filtering through the traffic on the A3 a few years ago, and some car drivers were trying to be difficult. A police biker parked at an intersection ahead pulled out ahead of me and was doing the same - they moved over rather quicker for him! A few got a finger wag. I got a thumbs up when I took my exit.