Hi, from the front of the car, sometimes I can both hear and feel a fast rhythmic "klonk" sound.

The feeling is as if I'm driving over something small - maybe like rail road tracks. The speed of it is around 5 times a second.

I believe it happens more often than when I'm not accelerating or having my foot on the gas.

It's a 2001 MPI.

Any ideas?

Tyre pressures OK ??

You need to eliminate things bit by bit. As ^ says, start with tyres (try swopping front/rear if nothing obvious), then look at exhaust mountings, check dogbone mount and then other engine/gb mounts, shock absorbers and console bushes. With any luck, you'll get no further than the tyres.

As viewer says, or try swapping the front tyres left to right unless you're running directional tyres.

Nah, tyres are fine. Don't think it's shock absorber related either.

How would the car react if it was failing console bushes?

If it was console bushes you'd tend to get noises when going over rough surfaces rather than a regular sound, also may sound squeaky rather than knocking until they fail completely.