the 854cc Yanmar burns about a half gal./hr. and would be plenty for a 1000# car. think small engine and lots of gears in case you come up to a big hill. it is reasonably smooth too i have one in my HPX gator which is 1400#.
the tractor market has diesels from 12 to over 500 HP.
the 854cc has 33 Lb-ft @ 2500
http://www.deere.com/en_GB/products/.../hpx_specs.pdf