Competition is stiff in the semi-rarefied air around $50,000. One can choose from Cadillac, Mercedes-Benz, BMW, Jaguar, Lexus and INFINITI. Of that august group, the INFINITI Q45 has had the most difficult time attracting and keeping a sizable audience. We've never quite understood that. The Q45 has style, performance, luxury; the whole nine yards. Perhaps the style has been the problem. It's lacked the conservative, classical luxury car look of Mercedes, BMW and Lexus. And Jaguar's style is a thing unto itself. For 1997, the INFINITI folks say the Q45 is clean-sheet-of-paper new. That's hard to see at a glance. Although the differences from last year's model are significant, they are subtle. The sheetmetal has been reshaped to give the more traditional look lacking in the past. And although the V8 has dropped in displacement, the power-to-weight ratio is unchanged, because the new car is lighter than its predecessor.