2008 Lexus IS-F

What does the F stand for? It's a question we were asked a lot during our year with the Lexus IS-F, which has F badges scattered liberally over the exterior and throughout the interior. Their quantity is perhaps not surprising, as F is what designates this as a special model, one that is quite different - and a lot more expensive - than the IS250/350 sedan on which it's based. You wouldn't want people confusing the two.

Other brands have used letters - such as R, S, M, V, and AMG - to identify their high-performance variants, but Lexus chose the letter F. The official rationale is somewhat convoluted: "Internally within our corporation, the F designation has signified specially designed vehicles, high-output powertrains, and development processes outside the norm," says Toyota PR man Craig Taguchi, adding that the Lexus project was internally known as Circle F and the original LS400 was called F1, for Flagship One.

In the case of the IS-F, it could also stand for Finally. After all, it took nearly two decades from the launch of Toyota's luxury division before Lexus saw fit to introduce a high-performance model. But never mind its official origins. After we settled in for a yearlong stint with the IS-F, we usually gave the obvious answer: F is for Fast.

Is it ever. And we couldn't help drinking from its deep reservoirs of speed. "I ran the IS-F up to triple digits on a deserted stretch of I-196," wrote one staffer during the car's first few weeks in the office. "It got there very quickly and the car was rock solid - and it felt like it still had more to give." Well, it did. In our performance tests, we reached an electronically governed top speed of 170 mph. We also recorded a 0-to-60-mph time of 4.7 seconds, just fractionally slower than our Four Seasons Audi RS4 (4.6 seconds) and the most recent Cadillac CTS-Vs we tested (4.4/4.5 seconds, automatic/manual). It's also right in the mix with the BMW M3 (factory figures of 4.5/4.7 seconds, automatic/manual) and the claimed time for the Mercedes-Benz C63 AMG (4.3 seconds).

As in all those cars, a big V-8 has been stuffed into a small sedan's engine bay. Seen elsewhere in the LS600hL, the 5.0-liter is modified for IS-F duty, pushing output from 389 hp to 416 hp at 6600 rpm, although torque drops by 14 lb-ft, to 371 lb-ft. Among the changes are new cylinder heads - courtesy of Yamaha - with titanium intake valves, hollow camshafts, and an oil-scavenge pump that expeditiously returns oil to the pan, ensuring adequate supplies during high-g cornering. A two-stage air intake opens a second passage at 3600 rpm, triggering a change in the engine note from mild to wild. Some editors thought the V-8's Jekyll-and-Hyde sound track was odd and contrived, but New York bureau chief Jamie Kitman said he "loved the sound of the V-8 when all hell breaks loose."