This 02 is a great car, and don't want to hafta trade up for economy. I'm wondering why Prions 2 years newer and 250 pounds fatter get 20% better gas mileage-and what does it take to get there. It's just a machine dammit, same basic engine even...where does the big difference come from? I see so many great posts here on repairs-but what does it take to tweak this thing till it performs like a gen2?
There is my short answer. The Prius lineage are: NHW10 - sold only in Japan and some 'gray' markets, it has the original 1.5L engine and first generation transaxle and first generation software. Compact sedan like an Echo. It used "D" cells. NHW11 - the 2001-03 models we see in North America, it has more power, 4500 redline, improved transaxle, and improved software. Compact sedan, it included North American emissions such as HC converter and bladder tank. The first prismatic traction battery modules, much better than the "D" cells but heat sensitive. NHW20 - the 2004-09 models, the apex of this series, it has more power, 5200 red line, lower drag transaxle, and improved software. Eliminated the HC converter, had an 'undocumented' EV mode. It also has substantially improved traction batteries with lower internal resistance and better terminal seals. It also is an aerodynamic, full-size, hatchback. ZVW30 - the 2010-current models, it has more power, more transaxle gearing, and improved software. It also includes cooled, EGR for leaner mixtures at high power; muffler pressure relief valve at high power settings, and; eliminated the engine belt with an electric driven water pump. Further improvements in the traction battery but I don't have the details. We see the biggest difference when comparing the NHW11 versus NHW20: Notice how the NHW20 and NHW11 meet in the 65-70 mph range. But on either side, the NHW20 walks away due to better transaxle, engine, and control laws. Above 70 mph, the drag is so high the NHW11 engine begins to run 'fuel enrichment' mode. Here is another collection of NHW11 and NHW20 points: In 2006, there was a marathon Prius stunt where a team of drivers drove a Prius ~1,200 miles over several days. Their log are the black dots in chart. It was summer and they 'tuned' the Prius for optimum performance. In contrast, the "gray" line represents my best estimate of NHW11 performance, mph vs MPG. Various benchmarks show this line has merit. However, these are 'warmed up' data values. The NHW11 warm-up is a thing of horror but can be mitigated. The key to tweaking NHW11 performance is addressing the problem of engine warm-up. Over the years, some of us have found 'tricks' to mitigate warm-up cost. But to understand you need to run a few benchmarks: On the first drive of the day (called 'cold start' regardless of outside temperature). Power ON but do not start the car Reset a trip meter and record ambient temperature (60F and above is great, lower than 60F requires special attention) Use a recording device to monitor the trip meter distance and MPG (you need at least 0.5 to 1.0 mile resolution) Start the car and drive a regular route. Load the data into a spreadsheet and calculate the MPG between every data points. You'll soon see the first 1-3 miles is horrible. This is the warm-up penalty that kills NHW11 performance. Crack that nut and the car will be much, much better as this was one area where the NHW20 control laws made a big improvement. Bob Wilson ps. Aren't you glad I didn't offer the 'long version?'
In real world city driving, without AC, I saw better mpg out of the Gen I (after the warm up penalty) but, overall, the Gen II beats it handily. The Gen II is just a better car. The one thing I did notice on the Gen I is that its easier to take off on all electric (due to the lower weight I'm sure). As for tweaking this thing, many have tried and many have failed. It is pretty much tweaked out thanks to Toyota's engineers.
I meant to say "HC converter," fixed. FYI, I took this photo last night: Due to the oversized tires, that is actually 105.8% * 68.0 MPG or 71.9 MPG. Bob Wilson
I don't know how you do it Bob but I guess its because your trip is 25+ minutes. Mine is only about 10-12 minutes so I don't get more than 2 five minute periods. My first is about 30 mpg's and the second is just above 50 (sometimes above 60). Your second 5 min is about 80, Jeeez!.
Funny you should mention this. Last night I was thinking about how to write up something based upon using just the existing Prius displays. If I do, I'll write it up in 'sticky' format; post it, and; petition the moderators to make it a sticky. Bob Wilson
have an 02 that I may change injectors. Runs like crap. Any ideas or warnings. I can probably do this job Thanks Don
I don't know where Robert Menci gets his facts from, but on the average and historically the Prius Gen 1 is known to get a little better overall MPGs than the Gen 2 did. Don't judge the overall common reliability and the MPG well maintained DD and serviced Gen 1 from somebody's experience with a poory maintained car or one that is in such age and disrepair that it needs restoration or salvage. My very well restored ang lovingly serviced Gen 1, as with a number of other Gen 1 owners I know, get and easy low 50s and over 60s MPG, without any special hyper-mile driving. Now that cold weather has set in, the MPG has very typically dropped to mid 40s to the lower 50s. That's normal.
