Heh, speedbumps at more than 30 in the Jeep can be interesting. You get slammed pretty hard, as being solid axle, it has a lot of unsprung weight. I slow down a bit, to around 20 - 30 mph, depending on the height and length of the bump. I know the suspension can take it, as it's usually pretty smooth if I judge it correctly, and it's a Jeep. However, the obnoxiously sharp (tallish, very short length) bumps in parking lots are usually a crawling affair, as they're too harsh to cross quickly.
I know a guy with a beat up 97 Saturn SL1 who just says "screw it" and takes them at 40+. I've seen him catch air that way
, but at least he's not wasting gas (even though that's not his intent).
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Call me crazy, but I actually try for mpg with this Jeep:
Typical driving: Back in Rochester for school, driving is 60 - 70% city