Powering the 2008 Buick Enclave is GM’s new 3.6-liter 275-hp V-6 with variable valve timing, a competitive engine, but not a class leader. The engine is mated to a new clutch-to-clutch 6-speed automatic transmission and either front or all-wheel drive. The new transmission promises both good acceleration and good fuel economy, the latter addressing a common complaint about SUVs, although GM did not estimate fuel economy.