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Interesting(ish) tangent - the UK fuel economy specs used to be published at a constant 56mph & 75mph. When the Mk3 Vauxhall Cavalier was launched in the late 1
by alvah 6y ago
Interesting(ish) tangent - the UK fuel economy specs used to be published at a constant 56mph & 75mph. When the Mk3 Vauxhall Cavalier was launched in the late 1980s, it had great (theoretical) fuel economy, much better than its rivals, but a couple of noticeable flat spots under acceleration. Turned out Vauxhall had leaned the fuel maps at the exact engine revs that corresponded to 56mph and 75mph in top gear...
- londons_explore 6y agoDefeat device...? Cheating...? Multi-billion pound fine?
- mft_ 6y agoTotally different, isn't it? Presumably the Vauxhall mentioned would provide exactly the measured MPG when driven at the correct speed by any owner in the real world - hence the 'flat spot' noticed. The defeat concept you're referring to (presumably VW's) was set to only function during a test, and not in the real world (AIUI).
- londons_explore 6y agoVW's defeat concept was set to function only at the exact RPM's used during the test. If a real-world customer were to use those RPM's and conditions, it would activate too. In fact a CCC talk showed that 5% of regular driving activated it. Perhaps about 5% of regular vauxhall driving was in those flat spots... Seems the same to me.
- mywittyname 6y agoMy old (14) Mustang had exactly the same thing: there was a very noticeable reduction in power at ~2000 RPMs. I always suspected that it was to improve highway fuel economy, as that's exactly where the engine was spinning at 74mph in sixth.