My father asked me why they don't make diesel hybrids. Does anyone know??

 

There are some diesel hybrids out there, but I think they're all limited test fleets for now.

One of the reasons is expense. Diesel engines are generally 1k more expensive than an equivalent gasoline engine. Making that diesel engine green (especially if you want to be able to sell it in places like CA) adds more $$ for the special emissions equipment.

Another is diesel engines are not as perfect a fit to hybridize than gas engines. Gas engines generally don't have alot of low end torque, something the electric motor in the hybrid can make up for. Diesel engines have plenty of torque to go around so you don't gain much torque wise by adding an electric motor.

Still I'd love to get a diesel hybrid some day, fill it up with biodiesel and be totally carbon neutral.

 

Good for you! Going from 18 to 30 to 45 is fantastic! You're just the kind of story I like to hear on this site.

Living dangerously, I see. It's not always a good idea to aggravate wounded animals, and any SUV owner standing at a gas pump is about as close to being wounded as people generally get. I'd rather feel sorry for them, even though it's a self-inflicted wound.

It's not just your Geo Metro- it's generally true that in any vehicle, the faster you go, the worse your gas mileage will be. This is because of air resistance, at the most basic level- you have to push aside more air, faster, and all that air is pushing back at you, applying a force that you have to have enough force in the opposite direction to overcome in order to move ahead, which takes more energy. That plays a big part in the reason why gas mileage drops at higher speeds.