It looks like the combination of $4/gallon gas and CAFE rules may have finally administered the coup de grace to GM's plans for new rear wheel drive replacements for its big sedans. GM had been planning to replace the Chevrolet Impala and Buick Lucerne with models based on the same Zeta rear wheel drive platform as the Pontiac G8 around 2010. However, it now appears that the front wheel drive Impala will remain in production at GM's Oshawa Ontario plant until at least 2012. The new contract between GM and the Canadian Autoworkers union specifies that the popular Impala will live on. Most likely it will now get a visual refresh around 2010 and probably some powertrain upgrades to improve efficiency. The fate of the Buick remains uncertain. The Hamtramck assembly plant that currently produces the Lucerne and Cadillac DTS is scheduled to shift over to building a Delta platform MPV and some car called the Volt in 2010. Based on the current draft of CAFE rules, it seems GM could have likely met the requirements with a Zeta platform vehicle with smaller, more efficient engines and perhaps a hybrid powertrain. The seemingly inexorable shift to even more efficient vehicles driven by higher gas prices is likely to continue outstripping regulatory requirements for the foreseeable future and all the automakers are having to adjust quickly.

[Source: Automotive News - Sub. req'd]

Less than a month after General Motors reportedly paused development of their future rear wheel dirve cars due to the potential for new fuel economy regulations, Vice-Chairman Bob Lutz says the programs will probably go ahead after all. The powertrain mix for these vehicles will probably be adjusted to a more efficient mix than originally anticipated. Lutz was interviewed for the Detroit Public TV program Autoline Detroit that will be on this Sunday and indicated that after an evaluation, the Zeta platform is back on track.

This means that instead of a V-8 heavy mix, the next generation of larger GM cars will probably rely more on six-cylinder engines. With the addition of direct injection on these engines, fuel economy could be improved while maintaining the needed performance levels. In addition, the passenger car variant of the new two-mode hybrid system would seem to find a natural home in these vehicles, providing decent performance and fuel economy. The recently announced 2.9L V-6 diesel that will appear in European market versions of the Cadillac CTS would also be a perfect fit in this platform. For reference the European BMW 530d with similar power gets 35 mpg(US) combined without the hybrid. A diesel V-6 two-mode hybrid Impala could conceivably get 40mpg!

[Source: Detroit News]