Redline is a Japanese anime film based around the story of racing driver JP taking part in the Redline - a futuristic no holds barred race. A fairly simple premise, complicated somewhat by various back stories, evil mafia's and a race location not particularly wanting of a race happening right there.
To try and sum it up with a few references, think the pod racing scene from Episode One (and yes, apologies for reminding you about the rest of that movie) turned up to eleven with some even wilder vehicles, a hint of akira and some beautifully done anime visuals. Gratuitously over the top in all the good ways that make for an entertaining blast of a film, with enough of a back story and hook to draw you in and keep you interested.
A film that I was slightly wary of in advance - it had the distinct possibility of being a bit generic, lacking storyline in favour of excitement and grand set pieces, but one that was pulled off perfectly and makes for a very entertaining film when you want something just slightly over the top and silly, while still being a genuinely good film.