Let's face it: it's hard to make a good feature film about car racing. It may be impossible. There hasn't been one yet. (I haven't seen Rush. The trailers didn't make me want to rush right out. ;-)) For me, LeMans is still the best. For the racing scenes, which have nothing to do with what normally makes a good film.
It's said that Steve McQueen was going for authenticity. He certainly achieved it in the action footage. These are the parts of the film I fast-forward to. (I fast-forward past the rest of it.) They were achieved without modern technology like lipstick cameras and computer-aided-graphics. And with such common (and usually lame) props as fake race cars. (Much, but not all, of the "exteriors" footage was shot at the actual race in 1970, before "scene" production for the movie began.)
The racing scenes are convincing and capture the feel of LeMans. It's a special treat, now, to see cars on the Mulsanne Straight before the chicanes went in, and between Arnage and White House (long since replaced by the Porsche Curves). The audio is fine--sometimes excellent. The opening scenes, where McQueen drives his 911 through the French countryside and past the LeMans Cathedral, are more meaningful to me since I've been there.
But, like all racing films, the plot is lame and the characters are flat. The wisdom of putting a racing buff (and accomplished driver) in charge of his own film as Producer/Director could be argued. LeMans took longer to make than expected, went over budget, and had to pulled together by a turnaround Director. McQueen couldn't stop fooling with it in the production phase.
Some of the minor characters have their moments. Fred Haltiner's Johann Ritter, contemplating retirement from racing, is poignant and convincing. Ronald Leigh-Hunt's David Townshend is a not-so-thinly-veiled David Yorke, John Wyer's real team manager. (The importance of team managers usually gets short shrift in racing films.)
But these characters and insights interest only racing geeks. The main characters in LeMans are not engaging. A good movie is about sympathetic (or at least interesting) people in interesting situations, who's "interior space" is explored. Vinny Gambini and Mona Lisa Vito will always be more interesting, and funnier, than a racing driver, racing. (I picked My Cousin Vinny because Marisa Tomei is brilliant in the climactic scene in the witness box. She passes muster with car buffs--and other viewers don't care.) In LeMans, the disembodied "announcer voice" with the Olympian tone, used to advance the plot and explain the obvious to non-buffs, is extremely annoying.
The heros in a racing film are the cars and the courses. For a racing fan, they can make for an absorbing half-hour film. But there's not enough meat on the bones to sustain feature length. It's painful to watch the main characters in LeMans because, in this modern era, we all know of racing drivers who lead interesting multi-dimensional lives away from the track.
Just the same, I still pop LeMans into the DVD player now and then. McQueen's perfectionism resulted in some of the best racing footage ever put into a can.