It must have some serious turbo boost to make 70+ hp at 1800 rpm. I would have never guessed that to be very efficient, at least for a gas engine.
1800 is a standard gen set speed, but only because they need to spin 60hz divided by a whole number. 3600 is pretty revved up for most motors, but 1800 isn't unusual for 4 liter per cylinder sets (a rather large engine).
So why a 3-banger? If you don't rev it up, and don't have to solidly mount it, even a single (with balancers) would be plenty smooth. Less cylinders means less waste. Perhaps it only makes 20 hp at 1800, and 70+ is the peak, which makes a lot more sense.
My idea for a mileage car's power train is like the Volt's in that it would be a plug-in series hybrid, front wheel drive. But the engine would be a turbo diesel, perhaps single cylinder for a small car. It and its motor-generator would be connected (via compter-controlled clutch) to the final drive gear. Essentially a manual transmission stuck in 5th, but with no extra gears to sap power. This would give an extra cruise mode where it syncs to road speed, with essentially zero drive train loss. The main electric motor would have its own clutch between its reduction gears and the final drive, so that you wouldn't have to spin it when at cruise. Also, you could disconnect it when it runs out of revs (the EV1 ran out at 70 or so I think) and let the engine and its motor carry you up to the aero limit.
Not to mention that Li-Ion only lasts a couple of years from the date of manufacture, at least in my experience.
They probably weren't managed properly. Li Ion batteries will rapidly lose capacity if their voltage gets too high or their temperature is too high(grid corrosion and other problems occur). Not properly regulated, Li Ion batteries can lose 20% of their capacity within the course of a year(a month in the more extreme cases).
Tesla's main engineering effort was a regulation system for its car's battery pack. Kept from getting too warm and with proper management, Li Ion will only lose 2% of capacity per year or so. It is feasible to build a Li Ion pack with a reasonable 7-10 year shelf life without using fancy batteries from Altair Nanotechnologies(and a third party has yet to verify their claims as well). It's all in the battery regulation system.
So why a 3-banger? If you don't rev it up, and don't have to solidly mount it, even a single (with balancers) would be plenty smooth.
Three cylinders balance much better than you realize without counter weights and a single cylinder produces a nasty power pulse and would be much tougher to start because of single cylinder high displacement compression load.
Reuters. GM has set an a target for production of an all-electric car in 2010, according to GM product chief and Vice Chairman Bob Lutz during media previews at the Geneva auto show. A running Volt (earlier post) prototype is expected by the end of 2007.
But then they'd have to engineer a torque-splitting device (transmission) that didn't infringe on Toyota's brilliant system and patents (which so far 2 other manufacturers - Ford and Nissan - have licensed, rather than try to invent their own flavour of the same thing)..
GM already has had those for several years as well. Look up the GM hybrid bus and Hybrid Silverado pickup. The hybrid bus is a huge gas saver while the pickup is aimed a bit more at function with the capability to serve as a generator for your house or on a worksite. Also look for their dual mode hybrid system that will be coming out on the SUV's and sedans in the next several years.