Or straight onto the london underground (tube) from heathrow into central london.. Picadilly line . you may need to change once depending on your exact destination. If you have it I can tell you which line and station.

Its a drivers thing.. i just hate London taxies [and expensive] besides most places are within 10 mins walk of a station or underground..

to plan your own journey try the TFL planner you will need the exact destination post code and the approximate time you wish to depart Heathrow [say 1 hour after landing]

wiz

Yes definately recommend the TFL route planner but as Brian says mosts stops are walkable in central london . There are many around EC1 and liverpool street station will get you to within 10/15 minutes walk of most places in that area. It's often just quicker to get out and walk from the most convenient tube station rather than change to a different line for the sake of an extra 5 or 10 minutes walk. All that up and down crowded escalators .

the average speed of traffic in London is 16 mph [around 24kph] if sitting in traffic taking in the fumes is comfort then possibly.. i always use public transport [rail and underground] for speed, if comfort is what you want then there are several companies which offer a chauffeur service which can be booked in advance

wiz

Heathrow is not really central London and unfortunately you have the worst part of the M25 + central london traffic to negotiate . Yes the tube is rammed at most points in the day too .No idea what sort of money you could be looking at but it is worth considering if you book a chaffeur service at a fixed price .

between 6 am and midnight... but the absolute worse is the commuting hours 7am-9.30 am and 4pm to 7 pm