The basic answer in our industry is, whatever drives the most traffic. Think deeper though.
Ads for dealerships resonate both long and short-term with consumers in both the fixed and variable departments. As car people, we always want immediate results and push hard to achieve that. However, we consider the ramifications of all advertising to provide a long-lasting, positive result that compliments the brand your store(s) require.
We always find that a balance approach to advertising in specific digital and traditional media works best. One size never fits all however. What works at one store may not even work down the street for someone else. We have proven this with intense market and demographic research as well as consumer focus group work.