Whilst a Venus surface rover could utilise more mechanical rather than electrical propulsion methods it still has to have some onboard electronics in order to take measurements and most importantly maintain radio communication with an orbiter to send back data. With surface temperatures of about 465 deg Celsius this is no easy task. Gallium Arsenide based electronics can operate at higher temperatures than silicon based electronics (over 300 deg C operation has been demonstrated for GaAs devices), but even so if the electronics is merely thermally insulated from the external Venus surface conditions it would only be able to operate for a few hours at best until the heat penetrates the insulation and raises the electronics temperature above its operating limit, so to operate continuously there would need to be active refrigeration powered by some source such as an RTG or even wind turbine as illustrated in some of the NASA contest entries. Alternatively at least for the radio transmitter an interesting possibility occurs to me - old fashioned thermionic valves aka "tubes" should be able to operate at Venusian ambient temperatures, so maybe Venus rovers should use those rather than solid state electronics, that really would be a "steampunk" rover!