By plane
There is a very small airfield (http://www.lemans.cci.fr/...) located near the circuit, with no regular connections to other major cities. As there is a direct TGV access from Paris Charles de Gaulle Airport, there is absolutely no point in trying to get to Le Mans by plane, unless you have a private or chartered small plane. Ryanair operate flights from London and Porto to Aeroport Tours Val de Loire, just outside the city of Tours approximately 100 km from Le Mans.
By train
The TGV stops in Le Mans, and many TGV West-bounded trains leaving from Paris stop in Le Mans.
From Gare Montparnasse in Paris, there are trains every hour or so, and the 210-km trip takes 55 min.
There is also a direct TGV service from Charles de Gaulle Airport through TGV bypassing Paris to go to Nantes or Bordeaux, the trip takes 90 min, and the ticket train to Le Mans can be combined with your incoming flight, as if it was a connecting domestic flight.
From Le Mans, you can easily access Brittany, Bordeaux or Nantes.
Some TGV trains run to and from Lille for Eurostar connections to and from London.
Regional trains give you access to or from neighboring towns of Angers, Tours or Laval.
By car
Le Mans has many good road links to the rest of the country. The A11 L'Oceane highway runs from Paris to Nantes via Le Mans, and the A81 from Le Mans heads West to Rennes. It takes roughly 2h from Paris to drive to Le Mans. The city of Chartres, halfway from Paris has a magnificient cathedral which deserves a stop.