Fiat is reviving the 600 as a small electric crossover, with a hybrid version to launch in mid-. gasoline engines: fiat seicento 0. 9l 5mt ( 39 hp) fiat seicento 1. the reborn seicento is twinned with the jeep avenger. 1l 5mt ( pdf 54 hp) complete timeline of fiat seicento models and generations, with seicento pdf photos, specs reference and production years. the seicento, or 600, was designed as a successor of sorts to the fiat 600 of the 1960s, which in practical terms meant that it was a little larger than the cinquecento of the 1990s that it.