These devices include manual counters, stopwatches, odometers, and digital clocks. Whitaker was skillful at resetting car odometers with a screwdriver. Volga taxicabs often have more than on their odometers, and several engine rebuilds. This may be done by odometers, gyroscope-assisted tilt sensors and other technologies. Some preproduction models were handmade, and featured 5-digit odometers. Modern cars often employ digital odometers specially designed to be difficult to tamper. There also exist mechanical-digit versions, like the style of car odometers where . By the early 2000s, mechanical odometers would be phased out on cars from major manufacturers. Both drivers had a full set of standard steering controls, even with separate odometers. It has two separate odometers besides total distance counter. Clayton's design, which he called the "roadometer", is the basis for most modern odometers. It is common for odometers to be off by several percent. These odometers are considered to be more secure than mechanical odometers.