I like what Mercedes is doing. Of course, it's very expensive.
Mercedes S500 Plug-In Hybrid Rated At 78 MPG | CleanTechnica
Intelligent HYBRID: anticipatory energy management system
The second-generation S-Class hybrids feature an anticipatory energy management system and thereby improve energy efficiency. The operating strategy of the hybrid drive system not only accounts for the current driving condition and driver input, but also adjusts to the likely route (inclines, downhill stretches, bends or speed limits) for the next eight kilometres. Intelligent HYBRID uses the navigation data from COMAND Online to manage the charging and discharging of the high-voltage battery. The goal is, for example, to use the energy content of the battery for propulsion ahead of a downhill stretch in order to recharge it while going downhill using recuperation.
Recuperative braking system: the electric motor as alternator
The largest potential for lowering the energy consumption of hybrid drive systems lies in maximising energy recovery during coasting and braking. Upon depressing the brake pedal the deceleration is initially effected by the electric motor and not by the disc brakes. The new S-Class is the first to use a recuperative braking system (RBS) of the second generation. It ensures an unnoticeable overlapping of the conventional mechanical brakes and the electric braking performance of the electric motor in alternator mode.
The driver’s desired braking power is recorded by a pedal-travel sensor. The deceleration is dependent on the driving condition and is split into a recuperative brake-force portion and a portion to be supplied by the wheel brakes. The brake pressure on the rear axle is controlled by the RBS dependent on the current recuperation potential of the powertrain.
In addition, the combustion engine is switched off any time the vehicle is coasting and its drag torque when rolling is used by the electric motor as recuperation torque. However, without depressing the brake pedal no additional deceleration torque is provided for charging the battery and the vehicle can “sail”. The combustion engine is to be used for charging the battery as little as possible and only at suitable and most efficient operating points.
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Mercedes S500 Plug-In Hybrid Rated At 78 MPG | CleanTechnica
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