Think about a pushbike.

The cyclist can produce a given amount of power, but the amount of torque can vary:
Start with the chain in the granny cog (the little one) on the pedal set and one rotation of the pedal will turn the back wheel (say) 2 times.

That is a lot easier to do than having the chain on the big cog, which might turn the rear wheel 3 times for each rotation of the pedal.

Both use the same power (BHP) but the little wheel needs less torque.

Then, once the bike is up to speed, you don't need as much torque to keep it moving at the same speed, so you go up to the big cog, using less torque. You also have to put less effort in for each rotation of the pedal while still maintaining the same speed.

That's why torque is a good thing to have lots of - to help with rapid accelaration, and BHP should be less important once you get to the desired speed.