To convert more browsers into buyers, auto marketers are revving up their online ad spending. eMarketer estimates that online automotive advertising, including spending by manufacturers, dealer associations and dealers, will hit $3.24 billion this year, or 11.4% of total US online ad spending. In 2012, spending will grow faster than it had the past five years, climbing 18% to $3.82 billion.

For a complete report on automotive advertising, available with eMarketer Total Access, click here.