Why not to rent a car in London or in a major European city

 London and other big cities (Paris, Rome, Amsterdam,etc)

 DO NOT ATTEMPT TO RENT A CAR!!!

Here are some reasons...

1.  Even if you are an experienced driver in the US or Canada driving is very different, especially in the U.K.  
2.  In Central London its almost impossible to find a good parking spot. Even if you do find one it will be very far away from your destination. Plus its very expensive for one tiny little spot.
3. Central London has a congestion charge for almost all vehicles. Cameras are set up all over the city. The charge is over $15 (American).
4. Dealing with an accident is not pleasant no matter the circumstances in the USA. In another country would be very unpleasant.  It will probably ruin your trip.
5. Traffic circles are very common. Plus its different on the opposite side of the road.
6. In the U.K. they drive on the opposite side of the road. Rules are different and more complicated.
7. European cities are laid out differently than American cities. Streets don't have as many lanes and no grid system.
8. London has a very good transportation system. The London Underground (their subway), iconic buses, black cabs, and walking will get you where you need to be.
9. If you want to venture outside of London take a coach or a train to a smaller city such as Oxford, Canterbury, or Salisbury. If you want to go to a rural area go out to a small town or city and rent from there or hire a driver.
10. Rental cars can be pricey and petrol (gas) is higher than it is in the USA.
11. Since your eyes are on the road you won't be able to look around at the sights. Let an experienced driver take you around.
12. European drivers are EXTREMELY AGGRESSIVE.
13. If you have been to New York City, Los Angeles, or Chicago... traffic and the drivers are much worse in Europe.