This is India's only warm-up game ahead of next week's first Test against England at Lord's, but there has been little to encourage coach Duncan Fletcher and his players so far as they struggle to adapt to English conditions.
After a rain delay of more than three hours, India were finally able to take the field on the second day, but the tourists must have finished up wishing it had kept on raining.
India's bowlers spent most of the first day being hit to all parts of Taunton as Somerset opener Arul Suppiah scored a century, while England Test captain Andrew Strauss -- guesting for the west country outfit -- and Nick Compton recorded half-centuries.
It was more of the same on Saturday as Suppiah took his total to 156 before he was caught by Rahul Dravid off the bowling of Sreesanth with the score on 356.
Chris Jones, who scored an unbeaten 51, moved the total onto 425-3 before Somerset declared to the relief of an Indian bowling attack without rested stars Ishant Sharma and Harbhajan Singh.
A strong Indian batting line-up including Dravid, Sachin Tendulkar and Gautam Gambhir should have been able to respond with big totals of their own on a flat pitch.
But left-arm seamer Willoughby had other ideas as he finished the day with figures of 5-50, while no Indian batsman passed 30.
Gambhir, returning to action after missing the recent West Indies tour with a shoulder injury, was first to go as he fell on 21 after edging Willoughby to wicketkeeper Jos Buttler.
Willoughby struck again to dismiss opener Abhinav Mukund with the score on 51.
That brought Tendulkar together with Dravid, but India's two star batsman failed to deliver.
Dravid was caught by James Hildreth off Willougby for 17 and then Yurav Singh departed for a duck to Willoughby.
Tendulkar couldn't stem the tide and he went for 26 as 19-year-old Craig Meschede claimed his opening first-class wicket.
India were 90-6 afer Peter Trego dismissed wicketkeeper Wriddhiman Saha and only Suresh Raina, who made 30, offered any resistance as they finished in danger of defeat on the third and final day.
Copyright AFP (Agence France-Presse), 2011