[Big Dave]

I’ll take a whack at this but first you do what design engineers do first: identify your customer and his mission.

Unless you want to design something that will sell 100 units or less a year, you have to design for the average Joe, not the purist. A MPG-purist would ride a faired-in street luge with an engine barely capable of 60 MPH, but “Average Joe” ain’t gonna plunk down his money for it.

Note the pronoun. This, even more than a pickup truck is a guy’s vehicle. How many females do we have on this forum? Most women would not drive a high-MPG car at gunpoint. Who do you think drives most SUVs?

Figure you have to design for a guy in his forties, no doubt a bit overweight (the Olympic gymnast market won’t support much sales), who is about six-five, who wears a suit (no acrobatics for entry/exit.)

It has to have a heater good for Saskatchawan and an air conditioner good for Phoenix.

It has to have Interstate performance that a non-purist can tolerate. 0-70 on less than 12 seconds. Remember, a high-MPG car is small. It is one thing for me to take my sweet time accelerating my one-ton F-350 (7,000 lb of very sturdy truck) and quite another for a guy in a 2,700 lb, low-slung car to do it. He’ll want to get up to speed quickly. We don’t need a Z06 ‘Vette, but a small car with M-B 240D acceleration ain’t gonna sell to the average Joe in the US.

You have to keep the price down. For a single-use vehicle you can’t really expect to sell them over $20,000. Use as many off-the-shelf components as possible. You are going to have to manufacture it for about 15% less than a Cobalt. High unit cost is what killed the first-generation Insight. Honda lost their shirt on every one they sold.

What I would do is to repeat automotive history. In 1907 Billy Durant thought the Oldsmobile (he had just bought the company) Curved Dash was too wide for the crummy roads of the time, so he has two dudes at the factory saw it in two and scab it back together to see if it could be made to be workable. It was and the narrower version sold well for its day. In Durant’s day the cars were mostly wooden. Today you do it on AutoCad.

I start with an EV-1 (beautiful car that was betrayed by sad-sack batteries) and narrow it down by 25% in front. I lengthen the wheelbase and make it a tandem two-seater. Aft of the passenger seat, I further narrow the car in plan view, maybe narrowing the rear axle track but definitely NOT going to a 2f1r trike arrangement. I use a FWD setup with a small (90-100 HP) turbodiesel and a dual-clutch manual transmission. With six or eight speeds this thing will accelerate smartly and turn a very low RPM once up to Interstate cruise. FWD should give decent snow handling. I raise the roofline about two inches to give the taller customer a chance to like the thing. This is why I only narrow the car by 25%. I retain enough width to make it fairly stable in crosswinds.

What you wind up with is a very roomy and potentially comfortable car that still has the low frontal area of a tandem car. I doubt the back seat gets used 100 hours in the service life of the car.

The roominess also gives the car scope for nice profitable electronic gizmos like GPS and a powerful sound system. Let’s not forget at least four cupholders.

The diesel is a necessity, as it gives high enough peak power to meet acceleration requirements but still use very little fuel at low loads (cruising).

No torque converters…ever.

I eschew the hybrid setup for initial cost reasons.

I use a single door (maybe a big Lambo door for tight parking places) for both seats. A single door reduces costs and simplifies the car’s structure – reducing cost.

Starting with a EV-1 (Cd = 0.19) and lengthening it and further tapering the aft part of the car, might get us under Cd = 0.16. Maybe regs allow use of CCTV instead of side mirrors by time this thing sees the light of day. We make some aero appliances like air dams and wheel skirts easily removable for operations in snowy climates.

By now, customers expect power steering and anti-lock power brakes. Purists can get along without them but average Joe wants those features.

A controllable front air opening is a nice feature that should not cost too much.

In light of the stuff Toyota is going through these days, I keep electronic cross connection to a minimum.

A see this as a car the average Joe can drive mindlessly and get 60 MPG and a good hypermiler can easily get 80 MPG or more.out of it.

I see four possible problems.

One. I doubt you could make this thing pass US crash safety standards weighing less than 2,500 lb.

Two. The EPA despises diesels. If the car is stuck with a gas-pig engine, reduce MPG by 25%.

Three. we have over-estimated the market for such cars. If it is going to be viable you’ll have to sell at least 30,000 units a year. The Excursion, even with a high per-unit profit was not commercially viable because they could only sell about 15,000 units a year.

Four. Even if you can manufacture this car for 15% less than a Cobalt, it may not make enough unit profit to cover legacy costs.

I thought about a modernized Pillbug, but folks in the US won’t tolerate rear engine cars anymore.