Ah, good ole fueleconomy.gov! When I found this site, I thought how nice that I would be able to find models with good mileage.
Only problem is that the EPA ratings are only a guildline.
COMPARISON ONE: xD Scion 5-spd -v- HHR auto: Both have about the same hwy mpg (33-34ish) but the Scion is capable of 50 mpg on flat interstate while the HHR can barely do 35 mpg on the flat. How do I know this? Because I DROVE BOTH CARS. I averaged 44.5 mpg with the Scion during a complete cross-country trip from Greensburg to Dubois PA which involved at best, 2-lane state highways. This included stop and go driving when I had to drive through small towns and also did some shopping in Dubois. There are people that claim high 40's lifetime mileage in Scion xB's.
COMPARISON TWO: Yes, the Buicks you reference in fueleconomy are completely lack luster and not worth mentioning - just like the mpg I got with my 88 Delta 88. However, the 27/44 that has been actually exhibited by the same models can only mean,
there must have existed unacknowledged variants.
I figure with the internet, it will be possible to find someone who can identify these specific 3.8s and why they produced such high mpg.
Fueleconomy is fair in that it also makes available original EPA estimates which were higher than current. I believe the earlier estimates were more accurate. The Scion/HHR discrepancy suggests that they may have stacked the hwy spec to bury
theoretical or
flat road mpg which is really unfortunate.
NOTE: My friend that owns the xD that I drove said that when the car was new, it was stuck in the "high 20's" tankful mpg. But over the next 3-4k miles, its mpg continuously got higher and higher until it always got over 40 mpg per tankful. Could it be that the EPA tested cars that are not broken in? Was my HHR too new?
Fueleconomy does bring the Geo Metro XFi and the Honda Civic Vx to the top of the list which is very good relatively speaking. However Geo Metro XFi mpg could use some comment: The new EPA rating is 43/52 while the old was 53/58 while actual driving is probably more like 43/58. People with Geo's almost universally get near 60 mpg on interstate trips. Some even break 60 (probably on flat, non-speeding, interstate trips).
I believe the old EPA hwy spec is more accurate for hwy.
The city/hwy definitions should perhaps be changed to worst/best case which really is more informative.
Anyhow, the search goes on.... and fueleconomy.gov is quite a useful site, nonetheless.