documentclass[a4paper12pt]{article}
usepackage{geometry}

makeatletter
def@maketitle{
raggedright
begin{center}
{Huge bfseries sffamily @title }\[4ex]
{Large  @author}\[4ex]
@date\[8ex]
end{center}}
makeatother

begin{document}

title{Report}
author{Author}
date{Septembre 2013}

maketitle

end{document}