The win was, however, not enough for Saurashtra to qualify for the knockouts as they finished third in Group D with 12 points behind Himachal Pradesh and Uttar Pradesh (both on 16 points).
Only top two teams from each of the four groups make it to the knock-out phase.
Bengal finished fifth in the six-team group with four points from five matches.
Electing to bat, Bengal notched up 243 for 5 in their allotted 50 overs but Saurashtra chased down the target with four overs to spare at the Saurashtra Cricket Association Stadium.
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Opener Abhimanyu Easwaran top-scored with a 48 while captain Manoj Tiwary (43) and Shreevats Goswami (42) were the other notable contributors for Bengal.
Left-arm spinner Dharmendrasinh Jadeja did bulk of the damage, finishing with 3 for 46 off 10 overs.
Saurashtra's chase was driven by Vyas, who put on a 136-run opening stand with Sheldon Jackson (50), before Cheteshwar Pujara's unbeaten 50 steered them home by reaching 246 for 4 in 46 overs.