I saw that episode of "Fifth Gear". I was shocked at the results. If I recall correctly, of all the modifications they did, adding the cleaner garnered the best result.
FWIW, I ran some cleaner through my car as I did'nt know what the previous owner used for fuel. I may run a bottle once a year. I've used Lucas before on my BMW and may again on my LS.
2008 LS460 Black/Black
Prestigious Society Bypass Module. Staggered 20" TSR Wheels/Falken FK452 Tires,painted calipers, LED "Audi Style" DRL's, Full LED interior, 5k HID bulbs, 20% tint