The Sequel is a fuel concept that GM unveiled in mid-2006. It's a crossover utility built on top of a skateboard type chassis that includes the fuel storage tanks, batteries, fuel cell stack, wheel motors and assorted control electronics. The original skateboard chassis concept in the form of the Autonomy concept several years ago was developed by a team led by Christopher Borroni-Bird who is the Director of Advanced Technology Vehicle Concepts for General Motors. Since the vehicles where first shown last year the control system has remained under continuous development by engineers trying to optimize the powertrain control strategy to maximize the range.
Continue reading about our Sequel adventure after the jump.
The team set out from the research center shortly after 7:00am on a predefined route with a mix of driving conditions through upstate New York including about 55 miles of freeway driving. The route carried us past the Finger Lakes, through the Catskills including many small towns and included lots of hill climbing. The plan called for each of the six journalists to spend about 100 miles behind the wheel of one of the two vehicles to get a feel for how they work in real world conditions.
Both Sequels were filled with hydrogen that had been generated not far from Rochester in Niagara Falls using hydro-electric power from the falls so no fossil fuels were used to power them that day. Things mostly went according to plan although we did have a few glitches along the way. Each of the Sequels carried one journalist, one engineer and either GM Vice President Larry Burns or Sequel Chief Engineer Mohsen Shabana. The engineer in the back seat was equipped with a laptop to monitor all the vehicle's vital signs which turned out to be good thing.
In order to ensure the safety of the fleet and the participants GM set some strict operating parameters. If anything got out of range the whole convoy would pull over immediately so the engineers could diagnose the problem. If they couldn't sort it out within five minutes, the other half of the team would go on and the stranded vehicle would either catch up or get loaded on trailer that tracked our route.
During the course of the 300-mile drive we had to pull over unexpectedly three times. In each case the vehicles ultimately got back underway and in each case the reason for stopping was apparent high battery temperatures. The issue on the vehicle that stopped twice turned out to be a faulty sensor which was replaced but the battery temperature in the other Sequel actually did get a bit too high.
The Sequel engineering team
Aside from the that the vehicles performed flawlessly and actually got better than expected fuel economy. The Sequel, like the other fuel cell vehicles I've driven, behaved very normally which is particularly impressive given the drive-by-wire nature of the Sequel. The Sequel has four wheel steering with a rack in the front that has an actuator and two individual actuators on the rear wheels. The brakes have electrically actuated friction brakes with regenerative braking blended in and throughout the drive never exhibited any out the ordinary behavior.
The Sequel has the fourth-generation GM fuel cell technology which is the same type used in the upcoming fuel cell Equinox that will be part of the Project Driveway program this fall. At the recent Shanghai Motor Show GM unveiled a version of the Volt concept with the new fifth generation stack which doubles the power density of the stack in the Sequel. Even with the now-superseded fuel cell stack technology. the challenge was to cover a distance of at least 300 miles.
As it turned out both vehicles ran the full distance arriving at Lyndhurst Castle in Tarrytown New York eight and a half hours after leaving Honeoye Falls having covered a little over 302 miles. Each Sequel still had at least 1kg of hydrogen left in the tank which would have carried the vehicles over forty more miles. Considering the driving conditions with traffic jams, construction zones and air conditioning running almost the whole way on a day that ended at eighty degrees this is quite an achievement.
No one else is known to have gone this far under these conditions on a single tankful of hydrogen before. The only really technical issues that we encountered were elevated temperatures in the lithium ion batteries. The batteries used in the Sequels are air cooled but talking to Larry Burns when we were approaching the end of the trek, he indicated that it's looking like liquid cooling is going to be required in order to achieve the robust thermal management that will be required for production applications.
At the finish line a clearly delighted Larry Burns spoke to the crowd of local schoolchildren and other onlookers who had awaited our arrival and told them this is just the beginning of the transformation of the automobile. He clearly believes in this technology because it will free us from dependency on oil. No matter what you think of hydrogen as an energy carrier, the fact is that a lot engineers and technicians have worked very hard for many years and achieved a lot. The Sequel is one of the most technologically advanced vehicles in the world and it works. Not all of the technology contained within these concepts will appear at the same time, but over time it will probably filter into the cars we all drive.