 Complete the following phrase:  For 1961, two MBM chassis were constructed, and fitted with Porsche Flat-4 engines, and initially driven in hillclimbs by Monteverdi himself. He then entered one of the cars in the 1961 Solitude Grand Prix, a non-championship Formula One race. Unable to set a representative time in practice, Monteverdi lined up on the grid at the back of the field, and retired with engine failure after just two laps. This car was subsequently written off in an accident at Hockenheim, and Monteverdi buried the wreckage, deciding against continuing with the project. He had entered the car for the 