At the end of November, Turkey's private sector had $151.5 billion worth of long maturity debt, up 9 percent since the end of 2012, and $42 billion worth of short term debt, up 35 percent. The most recent central bank data shows 57 percent of debt was in dollars and 36 percent in euros.
Excluding the financial sector, foreign debt stood at $86 billion, almost two thirds of which is held by services companies and 37 percent by industrials.
Carmaker Tofas will also be very much more cautious with investments, CEO Kamil Basaran said.
Turkey's Sabanci Group said it still aimed to keep the budget it had completed before the graft scandal emerged. But the chairman of its retail and insurance arm, Haluk Dincer, complained: "There is no predictability right now."
(Read more: Goldman Sachs: Cut your emerging markets exposure a third)
Even Turkey's exporter association TIM, which stands to benefit from a weaker lira, warned it would rather see a stable currency.
Suleyman Onatca, chairman of the Turkish Enterprise and Business Confederation, said the depreciation had caused difficulties particularly for small and medium-sized companies. "We hear banks are reluctant to reopen loans that have expired and have demanded additional guarantees," he said.
Onatca recalled an economic crisis in 2001, the most recent in a series that periodically hit Turkey before Erdogan's AK Party came to power. "We don't want to see companies falling like leaves as they did in 2001," he said, urging the government to reduce political tension.
"We want a Turkey which does not have a separation of powers problem, in which there is rule of law and confidence in every institution. This is the Turkey picture that domestic and foreign investors want to see," said Onatca.
Carmaker Oyak Renault said a weaker lira made its exports cheaper for now, but it could see input prices rise if its suppliers buy materials in euros.
Rainer Genes, the chief executive of Mercedes-Benz Turk, said his company was both an importer and exporter. "For us, the difficulty lies in the fluctuation, and combined with this in having less time for adaptation to the change, rather than in the weakness." he said. "The dimensions of the impact will become clear when the exchange rates are stabilised."
(Read more: Turkish Finance Minister: Protests a 'Hiccup' for Economy)
Erdogan has overseen strong economic growth in Turkey since coming to power in 2002, transforming its reputation after a series of unstable coalition governments in the 1990s ran into repeated balance of payments problems and economic crises.
But its external financing needs are considerable - Barclays estimates them at $217 billion this year, more than five times the central bank's net foreign exchange reserves - and it is vital to be able to keep borrowing on international capital markets at reasonable costs.
"Some German companies contacted us recently because they wanted to know what was happening ... We said the trend is not very promising, and there are expectations the lira could weaken further," said Alper Ucok, head of TUSIAD's Berlin office.
Foreign Direct Investment (FDI) doubled between 2005 and 2006, peaking at $22 billion in 2007 before dropping due to the global financial crisis. It recovered but then fell again in 2012 to $12.6 billion.
Ucok said some foreign investors were hesitating. "Some companies have even put their investment in question. Industrial investors with large FDI are concerned and wondering about draft projects," he added.
(Read more: Turkish Turmoil: Scenes From Turkey's Protests)
The head of TUSIAD warned last week about the impact on foreign investors of a recent spate of hefty fines against major companies and frequent legal changes in a public tender law. That earned him a rebuke from Erdogan that he was a "traitor".