LAUNCHED two weeks after the all-new S40 sedan upon which it's based, the V50 wagon strikes at the heart of Volvo's most dominant market: the compact prestige wagon segment. Fresh new arrivals from BMW, Audi, Mercedes and Alfa mean the new V50 won't have it all its own way - and limited supply will plague Volvo in the short term. But here is a premium medium wagon that both eschews the ride/handling problems of Volvo's recent past, undercuts its rivals considerably on price and offers the best performance in class.