This really is a MUCH larger variant of Circus Maximus in Three Dimensions.  I sat in on this 54mm (!) chariot race at Cold Wars 2000. 

S-304 Roman Circus

Hosted by Bill Acheson and the HAWKs. Using Roman Circus rules.

Return to Ancient Rome for a spin around the stadium. 54mm chariots race around a track 15’ long.

Scale: 54mm. Players: 8. Duration: 4 hrs. Location: PA

Bill, who is an afficienado of really, really big plastic soldiers, has collected several of the Marx plastic "Ben Hur" playsets, and made himself a huge (two tables wide, two long) map of the Circus Maximus board using pieces of felt.  The resulting game is awesome to behold and fun to play.  This picture should give you and idea of the sheer size fo the Ben Hur playset (manufactured by now defunct Marx toys):

The Ben Hur Playset from MARX TOYS

To get an idea of the scale, one of the upright citizens pictured in the foreground is about as long as your finger.  Marx also made a set called Ben Hur Deluxe, which is pictured here:

Another View... this time of Ben Hur Deluxe

Basically it adds more footsoldiers.

ROMAN CIRCUS rules are a commercial item, so I can't recreate it here.   I felt that it was akin to Circus Maximus "Lite."  You customize your chariots the same way as in CM, you expend Endurance to zoom around the track, you make attacks... sound familiar?  BTW, your humble webmeister won that event listed above... :-)

I doubt you're going to run out and buy seven or eight Ben Hur sets (at 150 plus dollars each, recreating a CM game could be an expensive proposition).  However, here's some links to 54mm plastic vendors that may be able to locate just the chariot sets.

The Toy Soldier Company (look on the playsets page)

Playsets Breakdown

The Soldier Shop

Landers Toys

Michigan Toy Soldier Company (has individual Chariot Teams for Sale)