The vocabulary used to classify hybrid drivetrains has been lagging considerably behind new developments, as Wikipedia’s article on the matter proves. The old parallel, serial, mild and plug-in hybrid categories do little to illuminate public understanding of the underlying technology, and much to confuse it. Enter the BYD Dual-Mode, VW “Twindrive” and, now, the AVL “Turbohybrid”. With cooperation from BMW, Bosch and LuK, AVL has developed a mild-ish hybrid drivetrain. The consortium claims it’s cheaper and more fun to drive than a “full hybrid” while offering nearly the same efficiency. Care to deep dive?
The system is built around a turbocharged, direct-injection 1.6-liter engine (tuned for a flat torque curve) coupled to a long-geared manual transmission and a clever electric drive strategy. Electric power replaces low-end torque lost to tall gearing. AVL also claims that turbo overboost maintains a steady charge. Even if you only have, say )slowly), a 15kW double layer capacitor module instead of a lithium-ion battery, you don’t loose [sic] no juice.
That’s how the boffins rolled during testing of their Stage One (v1.0?) system. Even without regenerative braking or a high-capacity battery, AVL claims that its BMW 320i mule was 24 percent more efficient (NEDC) than a stop-start equipped, naturally-aspirated 320i– at an estimated 150 percent of the price.
And though that doesn’t sound great, a certain unnamed 1.5 liter power-split hybrid (Prius) offered only 36 percent better efficiency than the NA 320i at (again, estimated) 300 percent of the price (to produce, of course). Those BMW badges are expensive.
Anyway, the kicker (claims AVL): the Turbohybrid 320i is more fun to drive than either a weedy NA four-banger Beemer or a Prius. And that I buy.
Check out their release for graphs of elasticity, tip-in, and other “fun to drive” proving stuff.