Complex sentence: Cars were entered in official trials to accumulate performance information for possible buyers; only the company driver and an official were permitted in the vehicle with the driver being required to undertake any necessary maintenance during the proceedings so Levitt had also to be proficient in mechanics.
Split into simpler sentences: Cars were entered in official trials to accumulate performance information for possible buyers; only the company driver and an official were permitted in the vehicle. The driver was required to undertake any necessary maintenance during the proceedings so Levitt also had to be proficient in mechanics.