One would think that having a car built in-house
enabled them to iterate that much quicker.
There tends to be a pretty clear separation between the self-driving sensors and brains ('the new stuff') and the car platform ('the old stuff').
As long as you're willing to have some sensors and actuators visible (i.e. you're working on a prototype rather than a consumer-ready product) there's not much technical value added from building a custom car vs modifying an existing one. Indeed, it can easily slow you down as now you have a bunch of work to do developing a new car.
The car that won the DARPA grand challenge was fairly close how it came off the production line - except for an off-the-shelf electrical actuator system developed for disabled drivers, an off-the-shelf secondary alternator to power all the sensors and computers, and a bunch of sensors bolted to the roof rack.
The reasons to build your own are business/PR rather than technical/development speed. For example they can make it look cute and unaggressive which might be good PR; or insist on a public transport style vandal proof design for an on-demand business model. These might be good reasons, but they're business reasons not technical reasons.
As long as you're willing to have some sensors and actuators visible (i.e. you're working on a prototype rather than a consumer-ready product) there's not much technical value added from building a custom car vs modifying an existing one. Indeed, it can easily slow you down as now you have a bunch of work to do developing a new car.
The car that won the DARPA grand challenge was fairly close how it came off the production line - except for an off-the-shelf electrical actuator system developed for disabled drivers, an off-the-shelf secondary alternator to power all the sensors and computers, and a bunch of sensors bolted to the roof rack.
The reasons to build your own are business/PR rather than technical/development speed. For example they can make it look cute and unaggressive which might be good PR; or insist on a public transport style vandal proof design for an on-demand business model. These might be good reasons, but they're business reasons not technical reasons.