https://www.motortrend.com/news/4wd-ver ... 3DBC496BCF
Now after reading this, I mostly agree with everything they've laid out. Problem is, vehicles like my SRX and STS don't cleanly fit into either category as described. However, at the end of the day, they are "AWD" due to not meeting the criteria for 4WD (no low range, no locked center diff). The 4WD vehicles listed are almost entirely trucks or truck based with a few exceptions:
Some of these are unibody platforms and Jeep has the distinction of apparently qualifying as true 4WD even in essentially crossover type vehicles as the Cherokee. The Grand Cherokee I'd argue is NOT truck based but a lot of truck capability was basically bolted onto the platform.Trucks and SUVs that currently offer true 4WD systems include:
Chevrolet Silverado 1500/2500/3500
Chevrolet Colorado
Chevrolet Tahoe/Suburban
Ford Expedition
Ford F-Series/Super Duty
Ford Ranger
GMC Sierra 1500/2500/3500
GMC Canyon
Jeep Cherokee
Jeep Gladiator
Jeep Grand Cherokee
Jeep Wrangler
Land Rover Discovery
Land Rover Range Rover/Sport
Lexus GX
Lexus LX
Mercedes-Benz G-Class
Nissan Frontier
Nissan Titan/XD
Ram 1500/2500/3500
Toyota 4Runner
Toyota Land Cruiser
Toyota Sequoia
Toyota Tacoma
Toyota Tundra
But back to the STS/SRX system. There is a transfer case, and it has open differential action that defaults to a 50/50 torque split. But there is no mechanical control to route power to any specific location as all of that is accomplished with the traction control system by braking (which is pretty effective in on-road situations). The SRX does have an optional limited slip rear diff and that probably does help the system perform. This was not available on the AWD STS.
4WD systems have drawbacks. They're typically bigger and heavier (often adding more than 200 pounds) than AWD systems
I think AWD added like 300 lbs on the Sigma cars. I think the key thing there is that FWD-based AWD systems (especially ones that are really just FWD vehicles with a temporary low torque AWD mode) are light. But the SRX/STS are rear drive cars with a full time 50/50 split. So components are stronger, with 100% of the mass in the rear area as the RWD vehicles of them, but adding a front drive system (and transfer case) that, again, can handle a 50/50 torque split, or presumably even higher to the front in certain situations. I do suspect that the stability control system limits overall engine torque enough so you'd never end up with anywhere near 100% going to the front or, for that matter, 100% to the rear, even though the driveline could handle that (though maybe the transfer case cannot, with its small aluminum case).Setting the electrified AWD systems aside for the moment, the front-drive-based AWD systems tend to be the lightest, most fuel-efficient setups available (typically weighing well under 200 pounds and reducing EPA combined economy by 1-3 mpg).