The current model (THS II) is pretty good. The next model, perhaps using LiION batteries and even plug-in charging, will probably be better. But excluding the plug-in charging, as that's "cheating" the efficiency, how much is there left to improve?

Lets assume "normal" driving (no P&G). The current model is EPA rated at 47 MPG. This is easy to get in summer temps. I've seen it vary from about 44 to 60. So lets go with the 47 MPG. How much room is there for improvement above that? Anybody know how much energy we're wasting?

Pearl is a
2007 Driftwood Pearl Prius
Package "B" (everything but leather, nav, and rear camera)

Several things come to mind:

• exhaust gas energy capture
• aerodynamic drag reduction
• weight reduction
• smart cruise control
• ICE improvements

Exhaust Gas Energy Capture

The exhaust gas heat could be captured to provide cabin heat in the winter. This will avoid ICE cooling and subsequent running to keep the ICE heat at an optimum temperature. It would use an independent coolant loop.

The exhaust heat could also feed an ammonium absorption cooler with the 'condenser' located in the rear bumper and a coolant loop. This would provide additional cooling in the summer to minimize AC loads.

Finally, a turbo-alternator with optional water injection could provide additional exhaust energy capture. This should provide a significant efficiency improvment at higher speeds.

Aerodynamic Drag

The wheel wells should have a cover that prevents air flow out into the stream. In the case of the front tires, an articulating mechanism to handle turning.

The engine compartment should be 'sealed' with control vanes letting in just the amount of air needed, augmented by fans, to cool the compartment and avoid heat soaking. At high speeds in cold weather, the air should pass smoothly around instead of being rammed into the compartment.

Articulating air dam and side skirts that descend at +45 miles per hour would further reduce high-speed drag. This requires careful design since it has to be tolerant of high-speed impact with road debre and ice. Alternatively, a high-speed 'squat' as the suspension gets 'shorter' at high speeds and 'stretches up' at low speeds or rough roads for more ground clearance.

An adaptive suspension could also include better high-frequency dampening so high-pressure tires, 90 psi, can be used. Properly tuned, it should a quiet, boat-like ride and incredibly hard tires.

Weight Reduction

The hood, doors, wheel rims and trunk lid should be carbon or carbon/glass composites. The seats should also be carbon or carbon/glass composites. When cost effective, the body should be carbon or carbon/glass composite.

Smaller gas tank since the mileage will be higher. Size the tank for 600 miles plus a reserve. Also, solve the variable gas tank problem with a small 'pony' tank with a very accurate report of the last gallon.

Smart Cruise Control

Give it two modes: strict speed control and 0-5 miles per hour, efficient operation range. The strict speed control works just like it does today. The 0-5 miles per hour efficient mode adjusts the speed down as much as 5 miles per hour to keep the ICE running as efficiently as possible.

An optional, smart cruise control will adjust the speed to match a vehicle in front while keeping at a safe following distance. This would be an extra price option since it entails active electronics. This will also include collision avoidance and possibly enhanced night vision systems.

ICE Improvements

Replace the mechanical water pump with an electric pump.

Provide an optional 'natural gas' fuel that allows the Prius to be a co-generator at home for heating, cooling and power using natural gas. This will ensure the vehicle is warmed up most mornings doing something useful, keeping the home powered and livable.

In vehicle lubricant viscosity and particle measurement and monitoring systems. Thus lubricant changes move to actual wear versus some arbitrary mileage or time value.

Incorporate coolant loops in the hood and quarter panels. Designed to isolate in the event of a leak, these would reduce the radiator drag by an improved heat exchange with the outside air.

I didn't mention 'plug-in' capabilities since those have already been addressed. Somewhat hard to identify but replace all bulbs with high efficiency, LEDs. Also, a built-in, rear window vanes that work as solar reflectors during the summer and absorbers during the winter yet are horizontal so they can be easily seen through.

Give me a day or so and I'll add some more.

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
Free speech, dialog and knowledge thrives without the poison of SPAM.

There's more from where that came from. Some of them Bob has mentioned already.

- direct injection or direct & port injection

- "Valvematic" (Toyota will roll this out soon on all engines). It's similar to BMW's Valvetronic system.

- VVT-iE (electronic control of the valve lift instead of mechanical as found on the LS600h L)

- weight reduction (magnesium framed seats like the smart fortwo, smaller components like the smaller inverter on the TCH)

- radiant heating using exhaust gases to help heat up the cabin quicker

- smaller and/or lighter battery

- aerodynamic windshield wipers (most new cars have them now)

- hide the washer nozzles beneath the hood (which means the rear of the hood is to be raised which also helps hide the wipers too)

- flatter underbody (if possible, just cover the whole underbody)

- may not be cost-effective but replace wing mirrors with cameras

- lighter spare wheel (not runflats.. those tyres are waaay heavier than standard tyres)

- more use of lightweight materials in the engine and even smoother finishes in the cylinders, pistons and other high friction areas

- Larger capacity battery to store more energy via regenerative braking

- more powerful electric motors for better regenerative braking

- tighter body panel gaps between doors/hatch and body

- a very small turbo so that a smaller engine displacement can be use and of course that means less turbo lag and less overheating issues (or use one of those new variable something... turbos that can change the amount of air intake)

Mods: EV mod, VVT-i emblem, sport pedals, OEM cargo mat, JDM Prius interior footwell lighting, Sylvania Silverstars 9003ST, DICE iPod kit, OEM all-weather mats, TomTom ONE v2, LED licence plate lights.