^ It was done because the V8 engines used are heavy duty engines. They have known reliability, and are easily modified for the grueling work they have to perform (transmission coolers, oil coolers, blasting cold a/c at idle, etc) Plus the body on frame design of the Crown Vic makes it withstand the rough road conditions. Theres a reason why just about every cab company, police department, gov't agency fleets use them. plus the parts are cheap and they are easy to repair.
They have Toyota minivans now, a few Toyota Priuses, 2 Lexus SUV's (believe it or not), and Ford Escape hybrid SUV's. As far as for taxi use goes, the Toyotas, etc don't hold up well at all. The mechanical breakdown rate is real high for them, and the toyota minivan chassis doesn't fare well at all on the NYC streets. The majority of failures at the T&LC inspection facility now are chassis issues with the Toyotas.
As for the London cabs.....there is a company that is starting to sell them here now. I *think* that one is being tested by the NYC Taxi and Limousine Comission to see how it fares. But after import duties, etc, they cost over $40,000 USD.
NYC taxis have to be retired after a number of years. A privately owned cab has to be retired after 5 years--a fleet owned after 3. Crown Vic taxi's cost around $22,000. So even though its still a financial burden to pay that, imagine having to pay over $40,000. Plus don't forget the other mandatory crap as well--meter installation/calibration, Roof light, partition, required decals, etc. And to top it off, credit card readers and GPS are going to become mandatory within a few years. So that's a couple of thousand dollars out of the owners pocket.
Me-I just plan on keeping the cab till it has to be retired. Then I'm going to lease the medallion out. The current rate is around $2,000 a month from a broker. Theres no way in hell I'm going to sell it. When my uncle had bought it in the '70's, he pais around $15,000 for it. At the last auction, they went for $360,000..............
Now if they would only bring the old Checkers back................Last one was built in 1981 and retired in the late 1990's. Now THAT was a workhorse that was built to take it.