GM has completely updated its trio of midsize SUVs, which means a new-generation Enclave is arriving for 2018. There are three available versions including the Avenir, a new name for the high-end variants, equivalent to Denali at GMC. There's just one engine, a 310-horsepower, 3.6L V6. Depending on the version, front-wheel drive is standard, but most people will choose all-wheel drive.