In 1988 Cosworth built the DFR , which was used in F1 by the smaller teams until 1991 . It scored its last points in 1990 . The DFZ was produced as an interim model , but in 1988 Cosworth created the DFV 's final evolution , the DFR , which soldiered on in F1 with smaller teams until 1991 , scoring its last points - including a pair of second places by Jean Alesi - with Tyrrell in 1990 .